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lammps/lib/poems/revolutejoint.cpp
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revolutejoint.cpp
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/*
*_________________________________________________________________________*
* POEMS: PARALLELIZABLE OPEN SOURCE EFFICIENT MULTIBODY SOFTWARE *
* DESCRIPTION: SEE READ-ME *
* FILE NAME: revolutejoint.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 "revolutejoint.h"
#include "point.h"
#include "matrixfun.h"
#include "body.h"
#include "fastmatrixops.h"
RevoluteJoint::RevoluteJoint(){
DimQandU(1);
Vect3 axis;
axis.Zeros();
axis(3) = 1;
SetAxisPK(axis);
}
RevoluteJoint::~RevoluteJoint(){
}
JointType RevoluteJoint::GetType(){
return REVOLUTEJOINT;
}
void RevoluteJoint::SetAxisK(VirtualMatrix& axis){
axis_k = axis;
axis_pk = pk_C_ko*axis_k;
}
void RevoluteJoint::SetAxisPK(VirtualMatrix& axis){
axis_pk = axis;
axis_k = T(pk_C_ko)*axis_pk;
}
bool RevoluteJoint::ReadInJointData(std::istream& in){
Vect3 axis;
in >> axis;
SetAxisPK(axis);
return true;
}
void RevoluteJoint::WriteOutJointData(std::ostream& out){
out << axis_pk;
}
Matrix RevoluteJoint::GetForward_sP(){
Vect3 v_kk;
// v_kk = axis x r
FastCross(point2->position,axis_k,v_kk);
// sP = [axis;v_kk]
return Stack(axis_k,v_kk);
}
void RevoluteJoint::UpdateForward_sP( Matrix& sP){
// sP is constant, do nothing.
}
Matrix RevoluteJoint::GetBackward_sP(){
Vect3 v_kk;
// v_kk = axis x r
FastCross(point1->position,axis_pk,v_kk);
// sP = [axis;v_kk]
return -Stack(axis_pk,v_kk);;
}
void RevoluteJoint::UpdateBackward_sP( Matrix& sP){
// sP is constant, do nothing.
}
void RevoluteJoint::ComputeLocalTransform(){
Mat3x3 ko_C_k;
FastSimpleRotation(axis_k,q.BasicGet(0),ko_C_k);
// pk_C_k = pk_C_ko * ko_C_k;
FastMult(pk_C_ko,ko_C_k,pk_C_k);
}
void RevoluteJoint::ForwardKinematics(){
Vect3 result1,result2,result3,result4,result5;
Vect3 pk_w_k;
// orientations
ComputeForwardTransforms();
// compute position vector r12
//r12 = point1->position - pk_C_k * point2->position;
FastMult(pk_C_k,point2->position,result1);
FastSubt(point1->position,result1,r12);// Jacks comment: needs flipping!!!
// 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 revolute joint qdot = u)
// qdot = u
FastAssign(u,qdot);
// angular velocities
//body2->omega = body1->omega + body1->n_C_k * axis_pk * u;
//pk_w_k = axis_k * u;
//body2->omega_k = T(pk_C_k) * body1->omega_k + pk_w_k;
double u_double = u.BasicGet(0);
FastMult(u_double,axis_pk,result1);
FastMult(body1->n_C_k,result1,result2);
FastAdd(body1->omega,result2,body2->omega);
FastMult(u_double,axis_k,pk_w_k);
FastTMult(pk_C_k,body1->omega_k,result1);
FastAdd(result1,pk_w_k,body2->omega_k);
// compute velocities
FastCross(body1->omega_k,r12,result1);
FastCross(point2->position,pk_w_k,result2);
FastAdd(body1->v_k,result1,result3);
FastTMult(pk_C_k,result3,result4);
FastAdd(result2,result4,body2->v_k);
FastMult(body2->n_C_k,body2->v_k,body2->v);
// compute state explicit angular acceleration
FastCross(body2->omega_k,pk_w_k,result1);
FastTMult(pk_C_k,body1->alpha_t,result2);
FastAdd(result1,result2,body2->alpha_t);
// compute state explicit acceleration
FastCross(body1->alpha_t,point1->position,result1);
FastCross(body1->omega_k,point1->position,result2);
FastCross(body1->omega_k,result2,result3);
FastTripleSum(body1->a_t,result1,result3,result4);
FastTMult(pk_C_k,result4,result5);
FastCross(point2->position,body2->alpha_t,result1);
FastCross(point2->position,body2->omega_k,result2);
FastCross(body2->omega_k,result2,result3);
FastTripleSum(result5,result1,result3,body2->a_t);
}
void RevoluteJoint::BackwardKinematics(){
Vect3 result1,result2,result3,result4,result5;
Vect3 k_w_pk;
// orientations
ComputeBackwardTransforms();
// compute position vector r21
//r21 = point2->position - k_C_pk * point1->position;
FastMult(k_C_pk,point1->position,result1);
FastSubt(point2->position,result1,r21);
// compute position vector r21
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 revolute joint qdot = u)
// qdot = u
FastAssign(u,qdot);
// angular velocities
//body1->omega = body2->omega - body2->n_C_k * axis_k * u;
//k_w_pk = - axis_pk * u;
//body1->omega_k = pk_C_k * body2->omega_k + k_w_pk;
double u_double = u.BasicGet(0);
FastMult(-u_double,axis_k,result1);
FastMult(body2->n_C_k,result1,result2);
FastAdd(body2->omega,result2,body1->omega);
FastMult(-u_double,axis_pk,k_w_pk);
FastMult(pk_C_k,body2->omega_k,result1);
FastAdd(result1,k_w_pk,body1->omega_k);
// compute velocities
FastCross(body2->omega_k,r21,result1);
FastCross(point1->position,k_w_pk,result2);
FastAdd(body2->v_k,result1,result3);
FastMult(pk_C_k,result3,result4);
FastAdd(result2,result4,body1->v_k);
FastMult(body1->n_C_k,body1->v_k,body1->v);
// compute state explicit angular acceleration
FastCross(body1->omega_k,k_w_pk,result1);
FastMult(pk_C_k,body2->alpha_t,result2);
FastAdd(result1,result2,body1->alpha_t);
// compute state explicit acceleration
FastCross(body2->alpha_t,point2->position,result1);
FastCross(body2->omega_k,point2->position,result2);
FastCross(body2->omega_k,result2,result3);
FastTripleSum(body2->a_t,result1,result3,result4);
FastMult(pk_C_k,result4,result5);
FastCross(point1->position,body1->alpha_t,result1);
FastCross(point1->position,body1->omega_k,result2);
FastCross(body1->omega_k,result2,result3);
FastTripleSum(result5,result1,result3,body1->a_t);
}
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