#include <chainiksolvervel_wdls.hpp>

Inheritance diagram for KDL::ChainIkSolverVel_wdls:

Public Member Functions
virtual int	CartToJnt (const JntArray &, const FrameVel &, JntArrayVel &)

virtual int	CartToJnt (const JntArray &q_in, const Twist &v_in, JntArray &qdot_out)

	ChainIkSolverVel_wdls (const Chain &chain, double eps=0.00001, int maxiter=150)

double	getEps () const

double	getLambda () const

double	getLambdaScaled () const

unsigned int	getNrZeroSigmas () const

int	getSigma (Eigen::VectorXd &Sout)

double	getSigmaMin () const

int	getSVDResult () const

void	setEps (const double eps_in)

void	setLambda (const double lambda)

void	setMaxIter (const int maxiter_in)

int	setWeightJS (const Eigen::MatrixXd &Mq)

int	setWeightTS (const Eigen::MatrixXd &Mx)

virtual const char *	strError (const int error) const

virtual void	updateInternalDataStructures ()

	~ChainIkSolverVel_wdls ()

Public Member Functions inherited from KDL::ChainIkSolverVel
virtual	~ChainIkSolverVel ()

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	~SolverI ()

Static Public Attributes
static const int	E_CONVERGE_PINV_SINGULAR = +100
	solution converged but (pseudo)inverse is singular More...

Private Attributes
const Chain &	chain

double	eps

Jacobian	jac

ChainJntToJacSolver	jnt2jac

double	lambda

double	lambda_scaled

int	maxiter

unsigned int	nj

unsigned int	nrZeroSigmas

Eigen::VectorXd	S

double	sigmaMin

int	svdResult

Eigen::VectorXd	tmp

Eigen::MatrixXd	tmp_jac

Eigen::MatrixXd	tmp_jac_weight1

Eigen::MatrixXd	tmp_jac_weight2

Eigen::MatrixXd	tmp_js

Eigen::MatrixXd	tmp_ts

Eigen::MatrixXd	U

Eigen::MatrixXd	V

Eigen::MatrixXd	weight_js

Eigen::MatrixXd	weight_ts

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

Implementation of a inverse velocity kinematics algorithm based on the weighted pseudo inverse with damped least-square to calculate the velocity transformation from Cartesian to joint space of a general KDL::Chain. It uses a svd-calculation based on householders rotations.

J# = M_q*Vb*pinv_dls(Db)*Ub'*M_x

where B = Mx*J*Mq

and B = Ub*Db*Vb' is the SVD decomposition of B

Mq and Mx represent, respectively, the joint-space and task-space weighting matrices. Please refer to the documentation of setWeightJS(const Eigen::MatrixXd& Mq) and setWeightTS(const Eigen::MatrixXd& Mx) for details on the effects of these matrices.

For more details on Weighted Pseudo Inverse, see : 1) [Ben Israel 03] A. Ben Israel & T.N.E. Greville. Generalized Inverses : Theory and Applications, second edition. Springer, 2003. ISBN 0-387-00293-6.

2) [Doty 93] K. L. Doty, C. Melchiorri & C. Boniveto. A theory of generalized inverses applied to Robotics. The International Journal of Robotics Research, vol. 12, no. 1, pages 1-19, february 1993.

Definition at line 63 of file chainiksolvervel_wdls.hpp.

Constructor & Destructor Documentation

◆ ChainIkSolverVel_wdls()

KDL::ChainIkSolverVel_wdls::ChainIkSolverVel_wdls	(	const Chain &	chain,
		double	eps = `0.00001`,
		int	maxiter = `150`
	)

explicit

Constructor of the solver

Parameters

chain	the chain to calculate the inverse velocity kinematics for
eps	if a singular value is below this value, its inverse is set to zero, default: 0.00001
maxiter	maximum iterations for the svd calculation, default: 150

Definition at line 28 of file chainiksolvervel_wdls.cpp.

◆ ~ChainIkSolverVel_wdls()

KDL::ChainIkSolverVel_wdls::~ChainIkSolverVel_wdls ( )

Definition at line 72 of file chainiksolvervel_wdls.cpp.

Member Function Documentation

◆ CartToJnt() [1/2]

virtual int KDL::ChainIkSolverVel_wdls::CartToJnt	(	const JntArray &	,
		const FrameVel &	,
		JntArrayVel &
	)

inlinevirtual

not (yet) implemented.

Implements KDL::ChainIkSolverVel.

Definition at line 105 of file chainiksolvervel_wdls.hpp.

◆ CartToJnt() [2/2]

int KDL::ChainIkSolverVel_wdls::CartToJnt	(	const JntArray &	q_in,
		const Twist &	v_in,
		JntArray &	qdot_out
	)

virtual

Find an output joint velocity qdot_out, given a starting joint pose q_init and a desired cartesian velocity v_in

Returns: E_NOERROR=svd solution converged in maxiter E_SVD_FAILED=svd solution failed E_CONVERGE_PINV_SINGULAR=svd solution converged but (pseudo)inverse singular

Note: if E_CONVERGE_PINV_SINGULAR returned then converged and can continue motion, but have degraded solution; If E_SVD_FAILED returned, then getSvdResult() returns the error code from the SVD algorithm.

Implements KDL::ChainIkSolverVel.

Definition at line 116 of file chainiksolvervel_wdls.cpp.

◆ getEps()

double KDL::ChainIkSolverVel_wdls::getEps ( ) const

inline

Request the value of eps

Definition at line 193 of file chainiksolvervel_wdls.hpp.

◆ getLambda()

double KDL::ChainIkSolverVel_wdls::getLambda ( ) const

inline

Request the value of lambda for the minimum

Definition at line 198 of file chainiksolvervel_wdls.hpp.

◆ getLambdaScaled()

double KDL::ChainIkSolverVel_wdls::getLambdaScaled ( ) const

inline

Request the scaled value of lambda for the minimum singular value 1-6

Definition at line 204 of file chainiksolvervel_wdls.hpp.

◆ getNrZeroSigmas()

unsigned int KDL::ChainIkSolverVel_wdls::getNrZeroSigmas ( ) const

inline

Request the number of singular values of the jacobian that are < eps; if the number of near zero singular values is > jac.col()-jac.row(), then the jacobian pseudoinverse is singular

Definition at line 178 of file chainiksolvervel_wdls.hpp.

◆ getSigma()

int KDL::ChainIkSolverVel_wdls::getSigma ( Eigen::VectorXd & Sout )

Request the six singular values of the Jacobian

Definition at line 108 of file chainiksolvervel_wdls.cpp.

◆ getSigmaMin()

double KDL::ChainIkSolverVel_wdls::getSigmaMin ( ) const

inline

Request the minimum of the first six singular values

Definition at line 183 of file chainiksolvervel_wdls.hpp.

◆ getSVDResult()

int KDL::ChainIkSolverVel_wdls::getSVDResult ( ) const

inline

Retrieve the latest return code from the SVD algorithm

Returns: 0 if CartToJnt() not yet called, otherwise latest SVD result code.

Definition at line 210 of file chainiksolvervel_wdls.hpp.

◆ setEps()

void KDL::ChainIkSolverVel_wdls::setEps ( const double eps_in )

Set eps

Definition at line 98 of file chainiksolvervel_wdls.cpp.

◆ setLambda()

void KDL::ChainIkSolverVel_wdls::setLambda ( const double lambda )

Set lambda

Definition at line 93 of file chainiksolvervel_wdls.cpp.

◆ setMaxIter()

void KDL::ChainIkSolverVel_wdls::setMaxIter ( const int maxiter_in )

Set maxIter

Definition at line 103 of file chainiksolvervel_wdls.cpp.

◆ setWeightJS()

int KDL::ChainIkSolverVel_wdls::setWeightJS ( const Eigen::MatrixXd & Mq )

Set the joint space weighting matrix

Parameters

weight_js joint space weighting symmetric matrix, default : identity. M_q : This matrix being used as a weight for the norm of the joint space speed it HAS TO BE symmetric and positive definite. We can actually deal with matrices containing a symmetric and positive definite block and 0s otherwise. Taking a diagonal matrix as an example, a 0 on the diagonal means that the corresponding joints will not contribute to the motion of the system. On the other hand, the bigger the value, the most the corresponding joint will contribute to the overall motion. The obtained solution q_dot will actually minimize the weighted norm sqrt(q_dot'*(M_q^-2)*q_dot). In the special case we deal with, it does not make sense to invert M_q but what is important is the physical meaning of all this : a joint that has a zero weight in M_q will not contribute to the motion of the system and this is equivalent to saying that it gets an infinite weight in the norm computation. For more detailed explanation : vince.nosp@m.nt.p.nosp@m.adois.nosp@m.@upm.nosp@m.c.fr

Returns: success/error code

Definition at line 76 of file chainiksolvervel_wdls.cpp.

◆ setWeightTS()

int KDL::ChainIkSolverVel_wdls::setWeightTS ( const Eigen::MatrixXd & Mx )

Set the task space weighting matrix

Parameters

weight_ts task space weighting symmetric matrix, default: identity M_x : This matrix being used as a weight for the norm of the error (in terms of task space speed) it HAS TO BE symmetric and positive definite. We can actually deal with matrices containing a symmetric and positive definite block and 0s otherwise. Taking a diagonal matrix as an example, a 0 on the diagonal means that the corresponding task coordinate will not be taken into account (ie the corresponding error can be really big). If the rank of the jacobian is equal to the number of task space coordinates which do not have a 0 weight in M_x, the weighting will actually not impact the results (ie there is an exact solution to the velocity inverse kinematics problem). In cases without an exact solution, the bigger the value, the most the corresponding task coordinate will be taken into account (ie the more the corresponding error will be reduced). The obtained solution will minimize the weighted norm sqrt(|x_dot-Jq_dot|'*(M_x^2)*|x_dot-Jq_dot|). For more detailed explanation : vince.nosp@m.nt.p.nosp@m.adois.nosp@m.@upm.nosp@m.c.fr

Returns: success/error code

Definition at line 86 of file chainiksolvervel_wdls.cpp.

◆ strError()

const char * KDL::ChainIkSolverVel_wdls::strError ( const int error ) const

virtual

Return a description of the latest error

Returns: if error is known then a description of error, otherwise "UNKNOWN ERROR"

Reimplemented from KDL::SolverI.

Definition at line 218 of file chainiksolvervel_wdls.cpp.

◆ updateInternalDataStructures()

void KDL::ChainIkSolverVel_wdls::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::ChainIkSolverVel.

Definition at line 54 of file chainiksolvervel_wdls.cpp.

Member Data Documentation

◆ chain

const Chain& KDL::ChainIkSolverVel_wdls::chain

private

Definition at line 219 of file chainiksolvervel_wdls.hpp.

◆ E_CONVERGE_PINV_SINGULAR

const int KDL::ChainIkSolverVel_wdls::E_CONVERGE_PINV_SINGULAR = +100

static

solution converged but (pseudo)inverse is singular

Definition at line 67 of file chainiksolvervel_wdls.hpp.

◆ eps

double KDL::ChainIkSolverVel_wdls::eps

private

Definition at line 226 of file chainiksolvervel_wdls.hpp.

◆ jac

Jacobian KDL::ChainIkSolverVel_wdls::jac

private

Definition at line 222 of file chainiksolvervel_wdls.hpp.

◆ jnt2jac

ChainJntToJacSolver KDL::ChainIkSolverVel_wdls::jnt2jac

private

Definition at line 220 of file chainiksolvervel_wdls.hpp.

◆ lambda

double KDL::ChainIkSolverVel_wdls::lambda

private

Definition at line 236 of file chainiksolvervel_wdls.hpp.

◆ lambda_scaled

double KDL::ChainIkSolverVel_wdls::lambda_scaled

private

Definition at line 237 of file chainiksolvervel_wdls.hpp.

◆ maxiter

int KDL::ChainIkSolverVel_wdls::maxiter

private

Definition at line 227 of file chainiksolvervel_wdls.hpp.

◆ nj

unsigned int KDL::ChainIkSolverVel_wdls::nj

private

Definition at line 221 of file chainiksolvervel_wdls.hpp.

◆ nrZeroSigmas

unsigned int KDL::ChainIkSolverVel_wdls::nrZeroSigmas

private

Definition at line 238 of file chainiksolvervel_wdls.hpp.

◆ S

Eigen::VectorXd KDL::ChainIkSolverVel_wdls::S

private

Definition at line 224 of file chainiksolvervel_wdls.hpp.

◆ sigmaMin

double KDL::ChainIkSolverVel_wdls::sigmaMin

private

Definition at line 240 of file chainiksolvervel_wdls.hpp.

◆ svdResult

int KDL::ChainIkSolverVel_wdls::svdResult

private

Definition at line 239 of file chainiksolvervel_wdls.hpp.

◆ tmp

Eigen::VectorXd KDL::ChainIkSolverVel_wdls::tmp

private

Definition at line 228 of file chainiksolvervel_wdls.hpp.

◆ tmp_jac

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::tmp_jac

private

Definition at line 229 of file chainiksolvervel_wdls.hpp.

◆ tmp_jac_weight1

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::tmp_jac_weight1

private

Definition at line 230 of file chainiksolvervel_wdls.hpp.

◆ tmp_jac_weight2

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::tmp_jac_weight2

private

Definition at line 231 of file chainiksolvervel_wdls.hpp.

◆ tmp_js

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::tmp_js

private

Definition at line 233 of file chainiksolvervel_wdls.hpp.

◆ tmp_ts

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::tmp_ts

private

Definition at line 232 of file chainiksolvervel_wdls.hpp.

◆ U

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::U

private

Definition at line 223 of file chainiksolvervel_wdls.hpp.

◆ V

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::V

private

Definition at line 225 of file chainiksolvervel_wdls.hpp.

◆ weight_js

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::weight_js

private

Definition at line 235 of file chainiksolvervel_wdls.hpp.

◆ weight_ts

Eigen::MatrixXd KDL::ChainIkSolverVel_wdls::weight_ts

private

Definition at line 234 of file chainiksolvervel_wdls.hpp.

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

Public Member Functions

Static Public Attributes

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ChainIkSolverVel_wdls()

◆ ~ChainIkSolverVel_wdls()

Member Function Documentation

◆ CartToJnt() [1/2]

◆ CartToJnt() [2/2]

◆ getEps()

◆ getLambda()

◆ getLambdaScaled()

◆ getNrZeroSigmas()

◆ getSigma()

◆ getSigmaMin()

◆ getSVDResult()

◆ setEps()

◆ setLambda()

◆ setMaxIter()

◆ setWeightJS()

◆ setWeightTS()

◆ strError()

◆ updateInternalDataStructures()

Member Data Documentation

◆ chain

◆ E_CONVERGE_PINV_SINGULAR

◆ eps

◆ jac

◆ jnt2jac

◆ lambda

◆ lambda_scaled

◆ maxiter

◆ nj

◆ nrZeroSigmas

◆ S

◆ sigmaMin

◆ svdResult

◆ tmp

◆ tmp_jac

◆ tmp_jac_weight1

◆ tmp_jac_weight2

◆ tmp_js

◆ tmp_ts

◆ U

◆ V

◆ weight_js

◆ weight_ts