user_Link3DForces.c File Reference

#include "math.h"
#include "mbs_data.h"

Functions
double *	user_Link3DForces (double PxF[4], double RxF[4][4], double VxF[4], double OMxF[4], double AxF[4], double OMPxF[4], MbsData *mbs_data, double tsim, int ixF)
	Compute an user-specified point to point force, with arbitrary line of action. More...

Function Documentation

user_Link3DForces()

double* user_Link3DForces	(	double	PxF[4],
		double	RxF[4][4],
		double	VxF[4],
		double	OMxF[4],
		double	AxF[4],
		double	OMPxF[4],
		MbsData *	s,
		double	tsim,
		int	ixF
	)

Compute an user-specified point to point force, with arbitrary line of action.

A 3D link force is attached from a body (called the parent body) to a second body (called children body). The parent and children bodies cannot be inverted as it change the definition of both the inputs arguments and outputs results.

For the documentation below, let:

• point "A" be the anchor point on the parent body;
• point "B" the anchor point on the children body;
• point "M" the mid-point between "A" and "B";
• frame [P], the frame attached to the parent body
• frame [C], the frame attached to the children body

The returned force/torque component are expressed in the frame [P] and applied on both parent and children body at the location of point "B".

Parameters

[in]	PxF	The vector "AB" (index starting at 1) with components expressed in frame [P].
[in]	RxF	The rotation matrix (index starting at 1) such as [C] = Rxf*[P].
[in]	VxF	The differential velocity vector (index starting at 1) with components expressed in frame [P]. The velocities are computed at the coordinates of point "M" linked to parent (Md_p), then linked to children (Md_c) body. The differential velocity vector is : Md_c - Md_p.
[in]	OMxF	The differential angular velocity vector (index starting at 1) with components expressed in frame [P]. It is the difference between the parent angular velocity and the children angular velocity.
[in]	AxF	The differential acceleration vector (index starting at 1) with components expressed in frame [P]. The accelerations are computed at the coordinates of point "M" linked to parent (Mdd_p), then linked to children (Mdd_c) body. The differential acceleration vector is : Mdd_c - Mdd_p.
[in]	OMPxF	The differential angular acceleration vector (index starting at 1) with components expressed in frame [P]. It is the difference between the parent angular acceleration and the children angular acceleration.
[in,out]	s	The MbsData structure of the model on which the force is computed.
[in]	tsim	The current time of the simulation
[in]	ixF	The ID identifying the computed link3D force.

Returns

A vector (of size 6, index starting at 1) with the content described for MbsData::l3DW The content of the returned vector Swr is [Fx; Fy; Fz; Mx; My; Mz]:

• Force components (expressed in frame [P]) : Fx, Fy, Fz
• Pure torque components (expressed in frame [P]) : Mx, My, Mz