// Get the quaternion from a source vector and a destination vector which specifies
// the rotation from one to the other. The vectors do not need to be normalized.
ChQuaternion<double> Q_from_Vect_to_Vect(const ChVector<double>& fr_vect, const ChVector<double>& to_vect) {
const double ANGLE_TOLERANCE = 1e-6;
ChQuaternion<double> quat;
double halfang;
double sinhalf;
ChVector<double> axis;
double lenXlen = fr_vect.Length() * to_vect.Length();
axis = fr_vect % to_vect;
double sinangle = ChClamp(axis.Length() / lenXlen, -1.0, +1.0);
double cosangle = ChClamp(fr_vect ^ to_vect / lenXlen, -1.0, +1.0);
// Consider three cases: Parallel, Opposite, non-collinear
if (std::abs(sinangle) == 0.0 && cosangle > 0) {
// fr_vect & to_vect are parallel
quat.e0() = 1.0;
quat.e1() = 0.0;
quat.e2() = 0.0;
quat.e3() = 0.0;
} else if (std::abs(sinangle) < ANGLE_TOLERANCE && cosangle < 0) {
// fr_vect & to_vect are opposite, i.e. ~180 deg apart
axis = fr_vect.GetOrthogonalVector() + (-to_vect).GetOrthogonalVector();
axis.Normalize();
quat.e0() = 0.0;
quat.e1() = ChClamp(axis.x(), -1.0, +1.0);
quat.e2() = ChClamp(axis.y(), -1.0, +1.0);
quat.e3() = ChClamp(axis.z(), -1.0, +1.0);
} else {
// fr_vect & to_vect are not co-linear case
axis.Normalize();
halfang = 0.5 * ChAtan2(sinangle, cosangle);
sinhalf = sin(halfang);
quat.e0() = cos(halfang);
quat.e1() = ChClamp(axis.x(), -1.0, +1.0);
quat.e2() = ChClamp(axis.y(), -1.0, +1.0);
quat.e3() = ChClamp(axis.z(), -1.0, +1.0);
}
return (quat);
}
void ChLinkPulley::UpdateTime (double mytime)
{
// First, inherit to parent class
ChLinkLock::UpdateTime(mytime);
ChFrame<double> abs_shaft1;
ChFrame<double> abs_shaft2;
((ChFrame<double>*)Body1)->TrasformLocalToParent(local_shaft1, abs_shaft1);
((ChFrame<double>*)Body2)->TrasformLocalToParent(local_shaft2, abs_shaft2);
ChVector<> dcc_w = Vsub(Get_shaft_pos2(),
Get_shaft_pos1());
// compute actual rotation of the two wheels (relative to truss).
Vector md1 = abs_shaft1.GetA()->MatrT_x_Vect(dcc_w);
md1.z = 0; md1 = Vnorm (md1);
Vector md2 = abs_shaft2.GetA()->MatrT_x_Vect(dcc_w);
md2.z = 0; md2 = Vnorm (md2);
double periodic_a1 = ChAtan2(md1.x, md1.y);
double periodic_a2 = ChAtan2(md2.x, md2.y);
double old_a1 = a1;
double old_a2 = a2;
double turns_a1 = floor (old_a1 / CH_C_2PI);
double turns_a2 = floor (old_a2 / CH_C_2PI);
double a1U = turns_a1 * CH_C_2PI + periodic_a1 + CH_C_2PI;
double a1M = turns_a1 * CH_C_2PI + periodic_a1;
double a1L = turns_a1 * CH_C_2PI + periodic_a1 - CH_C_2PI;
a1 = a1M;
if (fabs(a1U - old_a1) < fabs(a1M - old_a1))
a1 = a1U;
if (fabs(a1L - a1) < fabs(a1M - a1))
a1 = a1L;
double a2U = turns_a2 * CH_C_2PI + periodic_a2 + CH_C_2PI;
double a2M = turns_a2 * CH_C_2PI + periodic_a2;
double a2L = turns_a2 * CH_C_2PI + periodic_a2 - CH_C_2PI;
a2 = a2M;
if (fabs(a2U - old_a2) < fabs(a2M - old_a2))
a2 = a2U;
if (fabs(a2L - a2) < fabs(a2M - a2))
a2 = a2L;
// correct marker positions if phasing is not correct
double m_delta =0;
if (this->checkphase)
{
double realtau = tau;
//if (this->epicyclic)
// realtau = -tau;
m_delta = a1 - phase - (a2/realtau);
if (m_delta> CH_C_PI) m_delta -= (CH_C_2PI); // range -180..+180 is better than 0...360
if (m_delta> (CH_C_PI/4.0)) m_delta = (CH_C_PI/4.0); // phase correction only in +/- 45°
if (m_delta<-(CH_C_PI/4.0)) m_delta =-(CH_C_PI/4.0);
//***TODO***
}
// Move markers 1 and 2 to align them as pulley ends
ChVector<> d21_w = dcc_w - Get_shaft_dir1()* Vdot (Get_shaft_dir1(), dcc_w);
ChVector<> D21_w = Vnorm(d21_w);
this->shaft_dist = d21_w.Length();
ChVector<> U1_w = Vcross(Get_shaft_dir1(), D21_w);
double gamma1 = acos( (r1-r2) / shaft_dist);
ChVector<> Ru_w = D21_w*cos(gamma1) + U1_w*sin(gamma1);
ChVector<> Rl_w = D21_w*cos(gamma1) - U1_w*sin(gamma1);
this->belt_up1 = Get_shaft_pos1()+ Ru_w*r1;
this->belt_low1 = Get_shaft_pos1()+ Rl_w*r1;
this->belt_up2 = Get_shaft_pos1()+ d21_w + Ru_w*r2;
this->belt_low2 = Get_shaft_pos1()+ d21_w + Rl_w*r2;
// marker alignment
ChMatrix33<> maU;
ChMatrix33<> maL;
ChVector<> Dxu = Vnorm(belt_up2 - belt_up1);
ChVector<> Dyu = Ru_w;
ChVector<> Dzu = Vnorm (Vcross(Dxu, Dyu));
Dyu = Vnorm (Vcross(Dzu, Dxu));
maU.Set_A_axis(Dxu,Dyu,Dzu);
// ! Require that the BDF routine of marker won't handle speed and acc.calculus of the moved marker 2!
marker2->SetMotionType(ChMarker::M_MOTION_EXTERNAL);
marker1->SetMotionType(ChMarker::M_MOTION_EXTERNAL);
ChCoordsys<> newmarkpos;
// move marker1 in proper positions
newmarkpos.pos = this->belt_up1;
newmarkpos.rot = maU.Get_A_quaternion();
marker1->Impose_Abs_Coord(newmarkpos); //move marker1 into teeth position
// move marker2 in proper positions
newmarkpos.pos = this->belt_up2;
newmarkpos.rot = maU.Get_A_quaternion();
marker2->Impose_Abs_Coord(newmarkpos); //move marker2 into teeth position
double phase_correction_up = m_delta*r1;
double phase_correction_low = - phase_correction_up;
double hU = Vlenght(belt_up2- belt_up1) + phase_correction_up;
double hL = Vlenght(belt_low2- belt_low1) + phase_correction_low;
// imposed relative positions/speeds
deltaC.pos = ChVector<>(-hU, 0, 0);
deltaC_dt.pos = VNULL;
deltaC_dtdt.pos = VNULL;
deltaC.rot = QUNIT; // no relative rotations imposed!
deltaC_dt.rot = QNULL;
deltaC_dtdt.rot = QNULL;
}
void ChLinkGear::UpdateTime (double mytime)
{
// First, inherit to parent class
ChLinkLock::UpdateTime(mytime);
// Move markers 1 and 2 to align them as gear teeth
ChMatrix33<> ma1;
ChMatrix33<> ma2;
ChMatrix33<> mrotma;
ChMatrix33<> marot_beta;
Vector mx;
Vector my;
Vector mz;
Vector mr;
Vector mmark1;
Vector mmark2;
Vector lastX;
Vector vrota;
Coordsys newmarkpos;
ChFrame<double> abs_shaft1;
ChFrame<double> abs_shaft2;
((ChFrame<double>*)Body1)->TrasformLocalToParent(local_shaft1, abs_shaft1);
((ChFrame<double>*)Body2)->TrasformLocalToParent(local_shaft2, abs_shaft2);
Vector vbdist = Vsub(Get_shaft_pos1(),
Get_shaft_pos2());
Vector Trad1 = Vnorm(Vcross(Get_shaft_dir1(), Vnorm(Vcross(Get_shaft_dir1(),vbdist))));
Vector Trad2 = Vnorm(Vcross(Vnorm(Vcross(Get_shaft_dir2(),vbdist)), Get_shaft_dir2()));
double dist = Vlenght(vbdist);
// compute actual rotation of the two wheels (relative to truss).
Vector md1 = abs_shaft1.GetA()->MatrT_x_Vect(-vbdist);
md1.z = 0; md1 = Vnorm (md1);
Vector md2 = abs_shaft2.GetA()->MatrT_x_Vect(-vbdist);
md2.z = 0; md2 = Vnorm (md2);
double periodic_a1 = ChAtan2(md1.x, md1.y);
double periodic_a2 = ChAtan2(md2.x, md2.y);
double old_a1 = a1;
double old_a2 = a2;
double turns_a1 = floor (old_a1 / CH_C_2PI);
double turns_a2 = floor (old_a2 / CH_C_2PI);
double a1U = turns_a1 * CH_C_2PI + periodic_a1 + CH_C_2PI;
double a1M = turns_a1 * CH_C_2PI + periodic_a1;
double a1L = turns_a1 * CH_C_2PI + periodic_a1 - CH_C_2PI;
a1 = a1M;
if (fabs(a1U - old_a1) < fabs(a1M - old_a1))
a1 = a1U;
if (fabs(a1L - a1) < fabs(a1M - a1))
a1 = a1L;
double a2U = turns_a2 * CH_C_2PI + periodic_a2 + CH_C_2PI;
double a2M = turns_a2 * CH_C_2PI + periodic_a2;
double a2L = turns_a2 * CH_C_2PI + periodic_a2 - CH_C_2PI;
a2 = a2M;
if (fabs(a2U - old_a2) < fabs(a2M - old_a2))
a2 = a2U;
if (fabs(a2L - a2) < fabs(a2M - a2))
a2 = a2L;
// compute new markers coordsystem alignment
my = Vnorm (vbdist);
mz = Get_shaft_dir1();
mx = Vnorm(Vcross (my, mz));
mr = Vnorm(Vcross (mz, mx));
mz = Vnorm(Vcross (mx, my));
ChVector<> mz2, mx2, mr2, my2;
my2 = my;
mz2 = Get_shaft_dir2();
mx2 = Vnorm(Vcross (my2, mz2));
mr2 = Vnorm(Vcross (mz2, mx2));
ma1.Set_A_axis(mx,my,mz);
// rotate csys because of beta
vrota.x = 0.0; vrota.y = this->beta; vrota.z = 0.0;
mrotma.Set_A_Rxyz(vrota);
marot_beta.MatrMultiply(ma1, mrotma);
// rotate csys because of alpha
vrota.x = 0.0; vrota.y = 0.0; vrota.z = this->alpha;
if (react_force.x < 0) vrota.z = this->alpha;
else vrota.z = -this->alpha;
mrotma.Set_A_Rxyz(vrota);
ma1.MatrMultiply(marot_beta, mrotma);
ma2.CopyFromMatrix(ma1);
// is a bevel gear?
double be = acos(Vdot(Get_shaft_dir1(), Get_shaft_dir2()));
bool is_bevel= true;
if (fabs( Vdot(Get_shaft_dir1(), Get_shaft_dir2()) )>0.96)
is_bevel = false;
// compute wheel radii
// so that:
// w2 = - tau * w1
if (!is_bevel)
{
double pardist = Vdot(mr, vbdist);
double inv_tau = 1.0/tau;
if (!this->epicyclic)
{
r2 = pardist - pardist / (inv_tau + 1.0);
}
else
{
r2 = pardist - (tau * pardist)/(tau-1.0);
}
r1 = r2*tau; }
else
{
double gamma2;
if (!this->epicyclic)
{
gamma2 = be/(tau + 1.0);
}
else
{
gamma2 = be/(-tau + 1.0);
}
double al = CH_C_PI - acos (Vdot(Get_shaft_dir2(), my));
double te = CH_C_PI - al - be;
double fd = sin(te) * (dist/sin(be));
r2 = fd * tan(gamma2);
r1 = r2*tau;
}
// compute markers positions, supposing they
// stay on the ideal wheel contact point
mmark1 = Vadd(Get_shaft_pos2(), Vmul(mr2, r2));
mmark2 = mmark1;
contact_pt = mmark1;
// correct marker 1 position if phasing is not correct
if (this->checkphase)
{
double realtau = tau;
if (this->epicyclic)
realtau = -tau;
double m_delta;
m_delta = - (a2/realtau) - a1 - phase;
if (m_delta> CH_C_PI) m_delta -= (CH_C_2PI); // range -180..+180 is better than 0...360
if (m_delta> (CH_C_PI/4.0)) m_delta = (CH_C_PI/4.0); // phase correction only in +/- 45°
if (m_delta<-(CH_C_PI/4.0)) m_delta =-(CH_C_PI/4.0);
vrota.x = vrota.y = 0.0; vrota.z = - m_delta;
mrotma.Set_A_Rxyz(vrota); // rotate about Z of shaft to correct
mmark1 = abs_shaft1.GetA()->MatrT_x_Vect(Vsub(mmark1, Get_shaft_pos1() ));
mmark1 = mrotma.Matr_x_Vect(mmark1);
mmark1 = Vadd (abs_shaft1.GetA()->Matr_x_Vect(mmark1), Get_shaft_pos1() );
}
// Move Shaft 1 along its direction if not aligned to wheel
double offset = Vdot (this->Get_shaft_dir1(), (contact_pt - this->Get_shaft_pos1()) );
ChVector<> moff = this->Get_shaft_dir1() * offset;
if (fabs (offset) > 0.0001)
this->local_shaft1.SetPos( local_shaft1.GetPos() + Body1->Dir_World2Body(&moff) );
// ! Require that the BDF routine of marker won't handle speed and acc.calculus of the moved marker 2!
marker2->SetMotionType(ChMarker::M_MOTION_EXTERNAL);
marker1->SetMotionType(ChMarker::M_MOTION_EXTERNAL);
// move marker1 in proper positions
newmarkpos.pos = mmark1;
newmarkpos.rot = ma1.Get_A_quaternion();
marker1->Impose_Abs_Coord(newmarkpos); //move marker1 into teeth position
// move marker2 in proper positions
newmarkpos.pos = mmark2;
newmarkpos.rot = ma2.Get_A_quaternion();
marker2->Impose_Abs_Coord(newmarkpos); //move marker2 into teeth position
// imposed relative positions/speeds
deltaC.pos = VNULL;
deltaC_dt.pos = VNULL;
deltaC_dtdt.pos = VNULL;
deltaC.rot = QUNIT; // no relative rotations imposed!
deltaC_dt.rot = QNULL;
deltaC_dtdt.rot = QNULL;
}
