mbs_linearipk.c File Reference

#include "mbs_errors_names.h"
#include "mbs_linearipk.h"
#include "mbs_message.h"
#include "mbs_project_interface.h"

Functions
int	mbs_linearipk (double **GK, MbsLpk *lpk, MbsAux *aux, MbsData *s, int EqChoice)
	compute the linearized damping matrix Gr or stiffness matrix Kr for a given configuration (q,qd,qdd). More...
int	mbs_lineari_fct (double *x, double *Fx, MbsLpk *lpk, MbsAux *aux, MbsData *s, int EqChoice)
	compute the Fx vector for a given vector x. More...
MbsLpk *	mbs_new_lpk (MbsData *s, int nx, int nF)
	create a new lpk structure that is used to compute the linearized matrices Gr and Kr. More...
void	mbs_delete_lpk (MbsLpk *lpk)
	free memory of the lpk structure. More...

Detailed Description

This file implements the functions tangent computation of the system with the lpk approach.

Author

Robotran team

Original file by Q Docquier, 2016

(c) Universite catholique de Louvain

Function Documentation

mbs_delete_lpk()

void mbs_delete_lpk

(

MbsLpk *

lpk

)

free memory of the lpk structure.

Parameters

[in,out]

lpk

the MbsLpk structure to delete.

mbs_lineari_fct()

int mbs_lineari_fct	(	double *	x,
		double *	Fx,
		MbsLpk *	lpk,
		MbsAux *	aux,
		MbsData *	s,
		int	EqChoice
	)

compute the Fx vector for a given vector x.

The values in the vector x are set in the memory pointed by MbsLpk::x_ptr (typically the independents joints coordinates MbsData::q or velocities MbsData::qd).

NOTE: this function could be clearly improved by the use of a vector of pointer that either point the velocities or the positions.

Parameters

[in]	x	contains the independent position OR velocities OR the extra differential states.
[out]	Fx	contains the residual of the reduced equations of motion OR the extra set of constitutive ODE for the provided vector x.
[in]	lpk	computation structure used for the linearization.
[in]	aux	auxilary structure necessary for the computation of the reduced residual.
[in]	s	data structure, just used for the computation.
[in]	EqChoice	digit that indicates on which equations is performed the linearization: 1: on the reduced Equation of Motion; 2: on the user derivatives equations; 3: on the user added equilibrium equations.

Returns

Error status, <0 in case of failure.

mbs_linearipk()

int mbs_linearipk	(	double **	GK,
		MbsLpk *	lpk,
		MbsAux *	aux,
		MbsData *	s,
		int	EqChoice
	)

compute the linearized damping matrix Gr or stiffness matrix Kr for a given configuration (q,qd,qdd).

The compted matrix depend weither MbsLpk::x_ptr points to MbsData::q[MbsData::qu] or MbsData::qd[MbsData::qu].

NOTE: this function could be clearly improved by the use of a vector of pointer that either point the velocities or the positions.

Parameters

[out]	GK	contains the resulting linearized matrix (Gr or Kr).
[in]	lpk	computation structure used for the linearization.
[in]	aux	auxilary structure necessary for the computation of the reduced residual.
[in]	s	data structure containing the mbs configuration (q,qd,qdd).
[in]	EqChoice	digit that indicates on which equations is performed the linearization (see mbs_lineari_fct())

Returns

Error status, <0 in case of failure.

mbs_new_lpk()

MbsLpk* mbs_new_lpk	(	MbsData *	s,
		int	nx,
		int	nF
	)

create a new lpk structure that is used to compute the linearized matrices Gr and Kr.

Parameters

[in]	s	the data structure of the mbs.
[in]	nx	the number of variables
[in]	nF	the number of equations

Returns

An allocated and initialized new lpk structure.