// Get the time derivative from a quaternion, a speed of rotation and an axis, defined in _abs_ coords.
ChQuaternion<double> Qdt_from_AngAxis(const ChQuaternion<double>& quat, double angle_dt, const ChVector<double>& axis) {
ChVector<double> W;
W = Vmul(axis, angle_dt);
return Qdt_from_Wabs(W, quat);
}
ChQuaternion<double> AngleDTDT_to_QuatDTDT(AngleSet angset,
const ChVector<double>& mangles,
const ChQuaternion<double>& q) {
ChQuaternion<double> res;
ChQuaternion<double> qa, qb;
ChVector<double> ang0, angA, angB;
double hsquared = CH_LOWTOL;
ang0 = Quat_to_Angle(angset, q);
angA = Vsub(ang0, Vmul(mangles, hsquared));
angB = Vadd(ang0, Vmul(mangles, hsquared));
qa = Angle_to_Quat(angset, angA);
qb = Angle_to_Quat(angset, angB);
res = Qscale(Qadd(Qadd(qa, qb), Qscale(q, -2)), 1 / hsquared);
return res;
}
// Get the second time derivative from a quaternion, an angular acceleration and an axis, defined in _abs_ coords.
ChQuaternion<double> Qdtdt_from_AngAxis(double angle_dtdt,
const ChVector<double>& axis,
const ChQuaternion<double>& q,
const ChQuaternion<double>& q_dt) {
ChVector<double> Acc;
Acc = Vmul(axis, angle_dtdt);
return Qdtdt_from_Aabs(Acc, q, q_dt);
}
ChQuaternion<double> AngleDT_to_QuatDT(AngleSet angset,
const ChVector<double>& mangles,
const ChQuaternion<double>& q) {
ChQuaternion<double> res;
ChQuaternion<double> q2;
ChVector<double> ang1, ang2;
ang1 = Quat_to_Angle(angset, q);
ang2 = Vadd(ang1, Vmul(mangles, CH_LOWTOL));
q2 = Angle_to_Quat(angset, ang2);
res = Qscale(Qsub(q2, q), (1 / CH_LOWTOL));
return res;
}
double ChCollisionUtils::PointTriangleDistance(Vector B,
Vector A1,
Vector A2,
Vector A3,
double& mu,
double& mv,
int& is_into,
Vector& Bprojected) {
// defaults
is_into = 0;
mu = mv = -1;
double mdistance = 10e22;
Vector Dx, Dy, Dz, T1, T1p;
Dx = Vsub(A2, A1);
Dz = Vsub(A3, A1);
Dy = Vcross(Dz, Dx);
double dylen = Vlength(Dy);
if (fabs(dylen) < EPS_TRIDEGEN) // degenerate triangle
return mdistance;
Dy = Vmul(Dy, 1.0 / dylen);
ChMatrix33<> mA;
ChMatrix33<> mAi;
mA.Set_A_axis(Dx, Dy, Dz);
// invert triangle coordinate matrix -if singular matrix, was degenerate triangle-.
if (fabs(mA.FastInvert(mAi)) < 0.000001)
return mdistance;
T1 = mAi.Matr_x_Vect(Vsub(B, A1));
T1p = T1;
T1p.y() = 0;
mu = T1.x();
mv = T1.z();
mdistance = -T1.y();
if (mu >= 0 && mv >= 0 && mv <= 1.0 - mu) {
is_into = 1;
Bprojected = Vadd(A1, mA.Matr_x_Vect(T1p));
}
return mdistance;
}
void ChLinkSpring::UpdateForces(double mytime) {
// Inherit force computation:
// also base class can add its own forces.
ChLinkMarkers::UpdateForces(mytime);
spr_react = 0.0;
Vector m_force;
double deform = Get_SpringDeform();
spr_react = spr_f * mod_f_time->Get_y(ChTime);
spr_react -= (spr_k * mod_k_d->Get_y(deform) * mod_k_speed->Get_y(dist_dt)) * (deform);
spr_react -= (spr_r * mod_r_d->Get_y(deform) * mod_r_speed->Get_y(dist_dt)) * (dist_dt);
m_force = Vmul(Vnorm(relM.pos), spr_react);
C_force = Vadd(C_force, m_force);
}
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;
}
void ChLinkBrake::UpdateForces (double mytime)
{
// First, inherit to parent class
ChLinkLock::UpdateForces(mytime);
if (this->IsDisabled()) return;
// then, if not sticking,
if (this->brake_torque)
{
if (brake_mode == BRAKE_ROTATION)
{
if ( ((ChLinkMaskLF*)mask)->Constr_E3().IsActive() == false)
{
int mdir;
Vector mv_torque = Vmul(VECT_Z, this->brake_torque);
mdir = 0; // clockwise torque
if (Vdot(this->relWvel, mv_torque) > 0.0)
{
mv_torque = Vmul (mv_torque, -1.0); // keep torque always opposed to ang speed.
mdir = 1; // counterclockwise torque
}
if (mdir != this->last_dir)
this->must_stick = TRUE;
this->last_dir = mdir;
// +++ADD TO LINK TORQUE VECTOR
C_torque = Vadd(C_torque, mv_torque);
}
}
if (brake_mode == BRAKE_TRANSLATEX)
{
if ( ((ChLinkMaskLF*)mask)->Constr_X().IsActive() == false)
{
int mdir;
Vector mv_force = Vmul(VECT_X, this->brake_torque);
mdir = 0; // F--> rear motion: frontfacing break force
if (this->relM_dt.pos.x > 0.0)
{
mv_force = Vmul (mv_force, -1.0); // break force always opposed to speed
mdir = 1; // F<-- backfacing breakforce for front motion
}
if (mdir != this->last_dir)
this->must_stick = TRUE;
this->last_dir = mdir;
// +++ADD TO LINK TORQUE VECTOR
C_force = Vadd(C_force, mv_force);
}
}
}
// turn off sticking feature if stick ration not > 1.0
if (this->stick_ratio <= 1.0)
must_stick = FALSE;
}
