// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
void ChTrackShoeSinglePin::Connect(std::shared_ptr<ChTrackShoe> next) {
ChVector<> loc = m_shoe->TransformPointLocalToParent(ChVector<>(GetPitch() / 2, 0, 0));
if (m_index == 0) {
// Create and initialize a point-line joint (sliding line along X)
ChQuaternion<> rot = m_shoe->GetRot() * Q_from_AngZ(CH_C_PI_2);
auto pointline = std::make_shared<ChLinkLockPointLine>();
pointline->SetNameString(m_name + "_pointline");
pointline->Initialize(m_shoe, next->GetShoeBody(), ChCoordsys<>(loc, rot));
m_shoe->GetSystem()->AddLink(pointline);
} else {
// Create and initialize the revolute joint (rotation axis along Z)
ChQuaternion<> rot = m_shoe->GetRot() * Q_from_AngX(CH_C_PI_2);
auto revolute = std::make_shared<ChLinkLockRevolute>();
revolute->SetNameString(m_name + "_revolute");
revolute->Initialize(m_shoe, next->GetShoeBody(), ChCoordsys<>(loc, rot));
m_shoe->GetSystem()->AddLink(revolute);
}
}
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
void ChLinearDamperRWAssembly::Initialize(std::shared_ptr<ChBodyAuxRef> chassis, const ChVector<>& location) {
// Express the suspension reference frame in the absolute coordinate system.
ChFrame<> susp_to_abs(location);
susp_to_abs.ConcatenatePreTransformation(chassis->GetFrame_REF_to_abs());
// Transform all points and directions to absolute frame.
std::vector<ChVector<> > points(NUM_POINTS);
for (int i = 0; i < NUM_POINTS; i++) {
ChVector<> rel_pos = GetLocation(static_cast<PointId>(i));
points[i] = susp_to_abs.TransformPointLocalToParent(rel_pos);
}
// Create the trailing arm body. The reference frame of the arm body has its
// x-axis aligned with the line between the arm-chassis connection point and
// the arm-wheel connection point.
ChVector<> y_dir = susp_to_abs.GetA().Get_A_Yaxis();
ChVector<> u = susp_to_abs.GetPos() - points[ARM_CHASSIS];
u.Normalize();
ChVector<> w = Vcross(u, y_dir);
w.Normalize();
ChVector<> v = Vcross(w, u);
ChMatrix33<> rot;
rot.Set_A_axis(u, v, w);
m_arm = std::shared_ptr<ChBody>(chassis->GetSystem()->NewBody());
m_arm->SetNameString(m_name + "_arm");
m_arm->SetPos(points[ARM]);
m_arm->SetRot(rot);
m_arm->SetMass(GetArmMass());
m_arm->SetInertiaXX(GetArmInertia());
chassis->GetSystem()->AddBody(m_arm);
// Cache points and directions for arm visualization (expressed in the arm frame)
m_pO = m_arm->TransformPointParentToLocal(susp_to_abs.GetPos());
m_pA = m_arm->TransformPointParentToLocal(points[ARM]);
m_pAW = m_arm->TransformPointParentToLocal(points[ARM_WHEEL]);
m_pAC = m_arm->TransformPointParentToLocal(points[ARM_CHASSIS]);
m_pAS = m_arm->TransformPointParentToLocal(points[SHOCK_A]);
m_dY = m_arm->TransformDirectionParentToLocal(y_dir);
// Create and initialize the revolute joint between arm and chassis.
// The axis of rotation is the y axis of the suspension reference frame.
m_revolute = std::make_shared<ChLinkLockRevolute>();
m_revolute->SetNameString(m_name + "_revolute");
m_revolute->Initialize(chassis, m_arm,
ChCoordsys<>(points[ARM_CHASSIS], susp_to_abs.GetRot() * Q_from_AngX(CH_C_PI_2)));
chassis->GetSystem()->AddLink(m_revolute);
// Create and initialize the rotational spring torque element.
m_spring = std::make_shared<ChLinkRotSpringCB>();
m_spring->SetNameString(m_name + "_spring");
m_spring->Initialize(chassis, m_arm, ChCoordsys<>(points[ARM_CHASSIS], susp_to_abs.GetRot() * Q_from_AngX(CH_C_PI_2)));
m_spring->RegisterTorqueFunctor(GetSpringTorqueFunctor());
chassis->GetSystem()->AddLink(m_spring);
// Create and initialize the translational shock force element.
if (m_has_shock) {
m_shock = std::make_shared<ChLinkSpringCB>();
m_shock->SetNameString(m_name + "_shock");
m_shock->Initialize(chassis, m_arm, false, points[SHOCK_C], points[SHOCK_A]);
m_shock->RegisterForceFunctor(GetShockForceFunctor());
chassis->GetSystem()->AddLink(m_shock);
}
// Invoke the base class implementation. This initializes the associated road wheel.
// Note: we must call this here, after the m_arm body is created.
ChRoadWheelAssembly::Initialize(chassis, location);
}
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
void ChRoadWheel::Initialize(std::shared_ptr<ChBodyAuxRef> chassis,
std::shared_ptr<ChBody> carrier,
const ChVector<>& location) {
// Express the road wheel reference frame in the absolute coordinate system.
ChFrame<> wheel_to_abs(location);
wheel_to_abs.ConcatenatePreTransformation(chassis->GetFrame_REF_to_abs());
// Create and initialize the wheel body.
m_wheel = std::shared_ptr<ChBody>(chassis->GetSystem()->NewBody());
m_wheel->SetNameString(m_name + "_wheel");
m_wheel->SetPos(wheel_to_abs.GetPos());
m_wheel->SetRot(wheel_to_abs.GetRot());
m_wheel->SetMass(GetWheelMass());
m_wheel->SetInertiaXX(GetWheelInertia());
chassis->GetSystem()->AddBody(m_wheel);
// Set wheel contact material properties.
switch (m_wheel->GetContactMethod()) {
case ChMaterialSurface::NSC:
m_wheel->GetMaterialSurfaceNSC()->SetFriction(m_friction);
m_wheel->GetMaterialSurfaceNSC()->SetRestitution(m_restitution);
break;
case ChMaterialSurface::SMC:
m_wheel->GetMaterialSurfaceSMC()->SetFriction(m_friction);
m_wheel->GetMaterialSurfaceSMC()->SetRestitution(m_restitution);
m_wheel->GetMaterialSurfaceSMC()->SetYoungModulus(m_young_modulus);
m_wheel->GetMaterialSurfaceSMC()->SetPoissonRatio(m_poisson_ratio);
m_wheel->GetMaterialSurfaceSMC()->SetKn(m_kn);
m_wheel->GetMaterialSurfaceSMC()->SetGn(m_gn);
m_wheel->GetMaterialSurfaceSMC()->SetKt(m_kt);
m_wheel->GetMaterialSurfaceSMC()->SetGt(m_gt);
break;
}
// Create and initialize the revolute joint between wheel and carrier.
// The axis of rotation is the y axis of the road wheel reference frame.
m_revolute = std::make_shared<ChLinkLockRevolute>();
m_revolute->SetNameString(m_name + "_revolute");
m_revolute->Initialize(carrier, m_wheel,
ChCoordsys<>(wheel_to_abs.GetPos(), wheel_to_abs.GetRot() * Q_from_AngX(CH_C_PI_2)));
chassis->GetSystem()->AddLink(m_revolute);
}
