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prismaticjoint.cpp
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Thu, Aug 8, 16:48
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Sat, Aug 10, 16:48 (1 d, 23 h)
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rLAMMPS lammps
prismaticjoint.cpp
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/*
*_________________________________________________________________________*
* POEMS: PARALLELIZABLE OPEN SOURCE EFFICIENT MULTIBODY SOFTWARE *
* DESCRIPTION: SEE READ-ME *
* FILE NAME: prismaticjoint.cpp *
* AUTHORS: See Author List *
* GRANTS: See Grants List *
* COPYRIGHT: (C) 2005 by Authors as listed in Author's List *
* LICENSE: Please see License Agreement *
* DOWNLOAD: Free at www.rpi.edu/~anderk5 *
* ADMINISTRATOR: Prof. Kurt Anderson *
* Computational Dynamics Lab *
* Rensselaer Polytechnic Institute *
* 110 8th St. Troy NY 12180 *
* CONTACT: anderk5@rpi.edu *
*_________________________________________________________________________*/
#include "prismaticjoint.h"
#include "point.h"
#include "matrixfun.h"
#include "body.h"
#include "fastmatrixops.h"
PrismaticJoint
::
PrismaticJoint
(){
q
.
Dim
(
1
);
qdot
.
Dim
(
1
);
u
.
Dim
(
1
);
udot
.
Dim
(
1
);
}
PrismaticJoint
::~
PrismaticJoint
(){
}
JointType
PrismaticJoint
::
GetType
(){
return
PRISMATICJOINT
;
}
bool
PrismaticJoint
::
ReadInJointData
(
std
::
istream
&
in
){
in
>>
axis_pk
;
axis_k
=
T
(
pk_C_ko
)
*
axis_pk
;
// init the constant transforms
pk_C_k
=
pk_C_ko
;
k_C_pk
=
T
(
pk_C_k
);
return
true
;
}
void
PrismaticJoint
::
WriteOutJointData
(
std
::
ostream
&
out
){
out
<<
axis_pk
;
}
Matrix
PrismaticJoint
::
GetForward_sP
(){
Vect3
zero
;
zero
.
Zeros
();
// sP = [zero;axis]
return
Stack
(
zero
,
axis_k
);
}
void
PrismaticJoint
::
UpdateForward_sP
(
Matrix
&
sP
){
// sP is constant, do nothing.
}
Matrix
PrismaticJoint
::
GetBackward_sP
(){
Vect3
zero
;
zero
.
Zeros
();
// sP = [zero;axis]
return
-
Stack
(
zero
,
axis_pk
);
}
void
PrismaticJoint
::
UpdateBackward_sP
(
Matrix
&
sP
){
// sP is constant, do nothing.
}
void
PrismaticJoint
::
ComputeForwardTransforms
(){
ComputeForwardGlobalTransform
();
}
void
PrismaticJoint
::
ComputeBackwardTransforms
(){
ComputeBackwardGlobalTransform
();
}
void
PrismaticJoint
::
ComputeLocalTransform
(){
// the transform is constant, do nothing
}
void
PrismaticJoint
::
ForwardKinematics
(){
Vect3
result1
,
result2
,
result3
;
Vect3
d_pk
;
// orientations
ComputeForwardTransforms
();
// compute position vector r12
//r12 = point1->position + axis_pk * q - pk_C_k * point2->position;
FastMult
(
pk_C_k
,
point2
->
position
,
result1
);
FastMult
(
q
.
BasicGet
(
0
),
axis_pk
,
d_pk
);
FastTripleSumPPM
(
point1
->
position
,
d_pk
,
result1
,
r12
);
// compute position vector r21
FastNegMult
(
k_C_pk
,
r12
,
r21
);
// compute global location
// body2->r = body1->r + body1->n_C_k * r12;
FastMult
(
body1
->
n_C_k
,
r12
,
result1
);
FastAdd
(
body1
->
r
,
result1
,
body2
->
r
);
// compute qdot (for Prismatic joint qdot = u)
// qdot = u
FastAssign
(
u
,
qdot
);
// angular velocities
//body2->omega = body1->omega;
//body2->omega_k = T(pk_C_k) * body1->omega_k;
FastAssign
(
body1
->
omega
,
body2
->
omega
);
FastMult
(
k_C_pk
,
body1
->
omega_k
,
body2
->
omega_k
);
// compute velocities
Vect3
pk_v_k
;
Vect3
wxgamma
;
FastMult
(
u
.
BasicGet
(
0
),
axis_k
,
pk_v_k
);
FastMult
(
k_C_pk
,
body1
->
v_k
,
result1
);
FastCross
(
body2
->
omega_k
,
r12
,
wxgamma
);
FastTripleSum
(
result1
,
pk_v_k
,
wxgamma
,
body2
->
v_k
);
FastMult
(
body2
->
n_C_k
,
body2
->
v_k
,
body2
->
v
);
// compute state explicit angular acceleration
FastMult
(
k_C_pk
,
body1
->
alpha_t
,
body2
->
alpha_t
);
// compute state explicit acceleration
FastCross
(
r21
,
body1
->
alpha_t
,
result1
);
FastAdd
(
body1
->
a_t
,
result1
,
result2
);
FastMult
(
k_C_pk
,
result2
,
result1
);
FastCross
(
body2
->
omega_k
,
pk_v_k
,
result2
);
FastMult
(
2.0
,
result2
,
result3
);
FastCross
(
body2
->
omega_k
,
wxgamma
,
result2
);
FastTripleSum
(
result1
,
result2
,
result3
,
body2
->
a_t
);
}
void
PrismaticJoint
::
BackwardKinematics
(){
Vect3
result1
,
result2
,
result3
;
Vect3
d_k
;
// orientations
ComputeBackwardTransforms
();
// compute position vector r21
//r21 = point2->position + axis_k * q - k_C_pk * point1->position;
FastMult
(
k_C_pk
,
point1
->
position
,
result1
);
FastMult
(
-
q
.
BasicGet
(
0
),
axis_k
,
d_k
);
FastTripleSumPPM
(
point2
->
position
,
d_k
,
result1
,
r21
);
// compute position vector r12
FastNegMult
(
pk_C_k
,
r21
,
r12
);
// compute global location
// body1->r = body2->r + body2->n_C_k * r21;
FastMult
(
body2
->
n_C_k
,
r21
,
result1
);
FastAdd
(
body2
->
r
,
result1
,
body1
->
r
);
// compute qdot (for Prismatic joint qdot = u)
// qdot = u
FastAssign
(
u
,
qdot
);
// angular velocities
//body1->omega = body2->omega;
//body1->omega_k = pk_C_k * body2->omega_k;
FastAssign
(
body2
->
omega
,
body1
->
omega
);
FastMult
(
pk_C_k
,
body2
->
omega_k
,
body1
->
omega_k
);
// compute velocities
Vect3
k_v_pk
;
Vect3
wxgamma
;
FastMult
(
-
u
.
BasicGet
(
0
),
axis_pk
,
k_v_pk
);
FastMult
(
pk_C_k
,
body2
->
v_k
,
result1
);
FastCross
(
body1
->
omega_k
,
r21
,
wxgamma
);
FastTripleSum
(
result1
,
k_v_pk
,
wxgamma
,
body1
->
v_k
);
FastMult
(
body1
->
n_C_k
,
body1
->
v_k
,
body1
->
v
);
// compute state explicit angular acceleration
FastMult
(
pk_C_k
,
body2
->
alpha_t
,
body1
->
alpha_t
);
// compute state explicit acceleration
FastCross
(
r12
,
body2
->
alpha_t
,
result1
);
FastAdd
(
body2
->
a_t
,
result1
,
result2
);
FastMult
(
pk_C_k
,
result2
,
result1
);
FastCross
(
body1
->
omega_k
,
k_v_pk
,
result2
);
FastMult
(
2.0
,
result2
,
result3
);
FastCross
(
body1
->
omega_k
,
wxgamma
,
result2
);
FastTripleSum
(
result1
,
result2
,
result3
,
body1
->
a_t
);
}
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