// Get the time derivative from a quaternion, a speed of rotation and an axis, defined in _abs_ coords. public static ChQuaternion Qdt_from_AngAxis(ChQuaternion quat, double angle_dt, ChVector axis) { ChVector W; W = ChVector.Vmul(axis, angle_dt); return(Qdt_from_Wabs(W, quat)); }
/// Someone (ex. an ChExternalObject() ) may send this message to /// the marker to tell that time has changed (even if simulation is /// not running! - so it is different from the usual UpdateTime() -) public void UpdatedExternalTime(double prevtime, double mtime) { double mstep = mtime - prevtime; ChCoordsys m_rel_pos_dt = new ChCoordsys(new ChVector(0, 0, 0), new ChQuaternion(1, 0, 0, 0)); ChCoordsys m_rel_pos_dtdt = new ChCoordsys(new ChVector(0, 0, 0), new ChQuaternion(1, 0, 0, 0)); // do not try to switch on the M_MOTION_KEYFRAMED mode if // we are already in the M_MOTION_EXTERNAL mode, maybe because // a link point-surface is already moving the marker and // it will handle the accelerations by itself if (this.motion_type == eChMarkerMotion.M_MOTION_EXTERNAL) { return; } // otherwise see if a BDF is needed, cause an external 3rd party is moving the marker this.motion_type = eChMarkerMotion.M_MOTION_FUNCTIONS; // if POSITION or ROTATION ("rel_pos") has been changed in acceptable time step... if ((!(ChVector.Vequal(FrameMoving.coord.pos, last_rel_coord.pos)) || !(ChQuaternion.Qequal(FrameMoving.coord.rot, last_rel_coord.rot))) && (Math.Abs(mstep) < 0.1) && (mstep != 0)) { // ... and if motion wasn't caused by motion laws, then it was a keyframed movement! if ((motion_X.Get_y(mtime) == 0) && (motion_Y.Get_y(mtime) == 0) && (motion_Z.Get_y(mtime) == 0) && (motion_ang.Get_y(mtime) == 0) && (motion_X.Get_Type() == ChFunction.FunctionType.FUNCT_CONST) && (motion_Y.Get_Type() == ChFunction.FunctionType.FUNCT_CONST) && (motion_Z.Get_Type() == ChFunction.FunctionType.FUNCT_CONST) && (motion_ang.Get_Type() == ChFunction.FunctionType.FUNCT_CONST)) { // compute the relative speed by BDF ! m_rel_pos_dt.pos = ChVector.Vmul(ChVector.Vsub(FrameMoving.coord.pos, last_rel_coord.pos), 1 / mstep); m_rel_pos_dt.rot = ChQuaternion.Qscale(ChQuaternion.Qsub(FrameMoving.coord.rot, last_rel_coord.rot), 1 / mstep); // compute the relative acceleration by BDF ! m_rel_pos_dtdt.pos = ChVector.Vmul(ChVector.Vsub(m_rel_pos_dt.pos, last_rel_coord_dt.pos), 1 / mstep); m_rel_pos_dtdt.rot = ChQuaternion.Qscale(ChQuaternion.Qsub(m_rel_pos_dt.rot, last_rel_coord_dt.rot), 1 / mstep); // Set the position, speed and acceleration in relative space, // automatically getting also the absolute values, FrameMoving.SetCoord_dt(m_rel_pos_dt); FrameMoving.SetCoord_dtdt(m_rel_pos_dtdt); // update the remaining state variables this.UpdateState(); // remember that the movement of this guy won't need further update // of speed and acc. via motion laws! this.motion_type = eChMarkerMotion.M_MOTION_KEYFRAMED; } } // restore state buffers and that's all. last_time = ChTime; last_rel_coord = (ChCoordsys)FrameMoving.coord; last_rel_coord_dt = (ChCoordsys)FrameMoving.coord_dt; }
/// Updates torque for the impose torque mode public override void UpdateForces(double mytime) { // First, inherit to parent class base.UpdateForces(mytime); if (!IsActive()) { return; } // DEFAULTS set null torques mot_torque = 0; mot_retorque = 0; if (eng_mode == eCh_eng_mode.ENG_MODE_TORQUE) { // in torque mode, apply the torque vector to both m1 and m2 // - M= f(t) double my_torque = Get_tor_funct().Get_y(ChTime); if (impose_reducer) { my_torque = my_torque * Get_torque_w_funct().Get_y(mot_rerot_dt); mot_retorque = my_torque; mot_torque = mot_retorque * (mot_eta / mot_tau); } else { my_torque = my_torque * Get_torque_w_funct().Get_y(mot_rot_dt); mot_torque = my_torque; mot_retorque = mot_retorque * (mot_tau / mot_eta); } ChVector mv_torque = ChVector.Vmul(motion_axis, mot_torque); // +++ADD TO LINK TORQUE VECTOR C_torque = ChVector.Vadd(C_torque, mv_torque); } if ((eng_mode == eCh_eng_mode.ENG_MODE_ROTATION) || (eng_mode == eCh_eng_mode.ENG_MODE_SPEED) || (eng_mode == eCh_eng_mode.ENG_MODE_KEY_ROTATION)) { mot_torque = react_torque.z; mot_retorque = mot_torque * (mot_tau / mot_eta) + mot_rerot_dtdt * mot_inertia; } if (eng_mode == eCh_eng_mode.ENG_MODE_SPEED) { // trick: zeroes Z rotat. violation to tell that rot.position is always ok if (C.matrix.GetRows() != 0) { C.matrix.SetElement(C.matrix.GetRows() - 1, 0, 0.0); } } }
// Get the second time derivative from a quaternion, an angular acceleration and an axis, defined in _abs_ coords. public static ChQuaternion Qdtdt_from_AngAxis(double angle_dtdt, ChVector axis, ChQuaternion q, ChQuaternion q_dt) { ChVector Acc; Acc = ChVector.Vmul(axis, angle_dtdt); return(Qdtdt_from_Aabs(Acc, q, q_dt)); }
/// Inherits, then also adds the spring custom forces to the C_force and C_torque. public override void UpdateForces(double mytime) { // Inherit force computation: // also base class can add its own forces. base.UpdateForces(mytime); spr_react = 0.0; ChVector 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 = ChVector.Vmul(ChVector.Vnorm(relM.pos), spr_react); C_force = ChVector.Vadd(C_force, m_force); }
/// Include the rotational spring custom torque. public override void UpdateForces(double time) { // Allow the base class to update itself (possibly adding its own forces). base.UpdateForces(time); // Invoke the provided functor to evaluate torque. // NOTE: we implicitly assume that the kinematics are CONSISTENT with this // type of link! double angle = relAngle; double angle_dt = ChVector.Vdot(relWvel, relAxis); if (m_torque_fun != null) { m_torque = (m_torque_fun)[time, relAngle, angle_dt, this]; } // Add to existing torque. C_torque += ChVector.Vmul(relAxis, m_torque); }
/// Inherits, and updates the C_force and C_torque 'intuitive' forces, /// adding the effects of the contained ChLinkForce objects. /// (Default: inherits parent UpdateForces(), then C_force and C_torque are /// incremented with the Link::ChLinkForces objects) public override void UpdateForces(double mytime) { base.UpdateForces(mytime); // ** Child class can inherit this method. The parent implementation must // be called _before_ adding further custom forces. ChVector m_force; // = new ChVector(0, 0, 0); // initialize to zero the m1-m2 force/torque ChVector m_torque; // = new ChVector(0, 0, 0); // 'intuitive' vectors (can be transformed&added later into Qf) // COMPUTE THE FORCES IN THE LINK, FOR EXAMPLE // CAUSED BY SPRINGS // NOTE!!!!! C_force and C_torque are considered in the reference coordsystem // of marker2 (the MAIN marker), and their application point is considered the // origin of marker1 (the SLAVE marker) // 1)========== the generic spring-damper if (force_D != null && force_D.Get_active()) { double dfor; dfor = force_D.Get_Force((dist - d_restlength), dist_dt, ChTime); m_force = ChVector.Vmul(ChVector.Vnorm(relM.pos), dfor); C_force = ChVector.Vadd(C_force, m_force); } // 2)========== the generic torsional spring / torsional damper if (force_R != null && force_R.Get_active()) { double tor; // 1) the tors. spring tor = force_R.Get_Force(relAngle, 0, ChTime); m_torque = ChVector.Vmul(relAxis, tor); C_torque = ChVector.Vadd(C_torque, m_torque); // 2) the tors. damper double angle_dt = ChVector.Vlength(relWvel); tor = force_R.Get_Force(0, angle_dt, ChTime); m_torque = ChVector.Vmul(ChVector.Vnorm(relWvel), tor); C_torque = ChVector.Vadd(C_torque, m_torque); } // 3)========== the XYZ forces m_force = ChVector.VNULL; if (force_X != null && force_X.Get_active()) { m_force.x = force_X.Get_Force(relM.pos.x, relM_dt.pos.x, ChTime); } if (force_Y != null && force_Y.Get_active()) { m_force.y = force_Y.Get_Force(relM.pos.y, relM_dt.pos.y, ChTime); } if (force_Z != null && force_Z.Get_active()) { m_force.z = force_Z.Get_Force(relM.pos.z, relM_dt.pos.z, ChTime); } C_force = ChVector.Vadd(C_force, m_force); // 4)========== the RxRyRz forces (torques) m_torque = new ChVector(0, 0, 0); if (force_Rx != null && force_Rx.Get_active()) { m_torque.x = force_Rx.Get_Force(relRotaxis.x, relWvel.x, ChTime); } if (force_Ry != null && force_Ry.Get_active()) { m_torque.y = force_Ry.Get_Force(relRotaxis.y, relWvel.y, ChTime); } if (force_Rz != null && force_Rz.Get_active()) { m_torque.z = force_Rz.Get_Force(relRotaxis.z, relWvel.z, ChTime); } C_torque = ChVector.Vadd(C_torque, m_torque); }
public override void UpdateForces(double mytime) { // First, inherit to parent class base.UpdateForces(mytime); if (this.IsDisabled()) { return; } // then, if not sticking, if (this.brake_torque != 0) { if (brake_mode == eChBrmode.BRAKE_ROTATION) { if (((ChLinkMaskLF)mask).Constr_E3().IsActive() == false) { int mdir; ChVector mv_torque = ChVector.Vmul(ChVector.VECT_Z, this.brake_torque); mdir = 0; // clockwise torque if (ChVector.Vdot(this.relWvel, mv_torque) > 0.0) { mv_torque = ChVector.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 = ChVector.Vadd(C_torque, mv_torque); } } if (brake_mode == eChBrmode.BRAKE_TRANSLATEX) { if (((ChLinkMaskLF)mask).Constr_X().IsActive() == false) { int mdir; ChVector mv_force = ChVector.Vmul(ChVector.VECT_X, this.brake_torque); mdir = 0; // F-. rear motion: frontfacing break force if (this.relM_dt.pos.x > 0.0) { mv_force = ChVector.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 = ChVector.Vadd(C_force, mv_force); } } } // turn off sticking feature if stick ration not > 1.0 if (this.stick_ratio <= 1.0) { must_stick = false; } }
/// Get the master coordinate system for the assets (this will return the /// absolute coordinate system of the 'master' marker2) // public override ChFrame<double> GetAssetsFrame(int nclone = 0) { return marker2.GetAbsFrame(); } // // UPDATING FUNCTIONS // /// Updates auxiliary vars relM, relM_dt, relM_dtdt, /// dist, dist_dt et simila. public virtual void UpdateRelMarkerCoords() { // FOR ALL THE 6(or3) COORDINATES OF RELATIVE MOTION OF THE TWO MARKERS: // COMPUTE THE relM, relM_dt relM_dtdt COORDINATES, AND AUXILIARY DATA (distance,etc.) ChVector PQw = ChVector.Vsub(marker1.GetAbsCoord().pos, marker2.GetAbsCoord().pos); ChVector PQw_dt = ChVector.Vsub(marker1.GetAbsCoord_dt().pos, marker2.GetAbsCoord_dt().pos); ChVector PQw_dtdt = ChVector.Vsub(marker1.GetAbsCoord_dtdt().pos, marker2.GetAbsCoord_dtdt().pos); dist = ChVector.Vlength(PQw); // distance between origins, modulus dist_dt = ChVector.Vdot(ChVector.Vnorm(PQw), PQw_dt); // speed between origins, modulus. ChVector vtemp1; // for intermediate calculus ChVector vtemp2; ChQuaternion qtemp1; // ChMatrixNM<IntInterface.Three, IntInterface.Four> relGw = new ChMatrixNM<IntInterface.Three, IntInterface.Four>(0); /* ChQuaternion q_AD; * ChQuaternion q_BC; * ChQuaternion q_8; * ChVector q_4;*/ ChQuaternion temp1 = marker1.FrameMoving.GetCoord_dt().rot; ChQuaternion temp2 = marker2.FrameMoving.GetCoord_dt().rot; if (ChQuaternion.Qnotnull(temp1) || ChQuaternion.Qnotnull(temp2)) { q_AD = // q'qqq + qqqq' ChQuaternion.Qadd(ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord_dt().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.GetBody().BodyFrame.GetCoord().rot), ChQuaternion.Qcross((marker1.GetBody().BodyFrame.GetCoord().rot), (marker1.FrameMoving.GetCoord().rot)))), ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.GetBody().BodyFrame.GetCoord().rot), ChQuaternion.Qcross((marker1.GetBody().BodyFrame.GetCoord().rot), (marker1.FrameMoving.GetCoord_dt().rot))))); } else { //q_AD = ChQuaternion.QNULL; q_BC = // qq'qq + qqq'q ChQuaternion.Qadd(ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.GetBody().BodyFrame.GetCoord_dt().rot), ChQuaternion.Qcross((marker1.GetBody().BodyFrame.GetCoord().rot), (marker1.FrameMoving.GetCoord().rot)))), ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.GetBody().BodyFrame.GetCoord().rot), ChQuaternion.Qcross((marker1.GetBody().BodyFrame.GetCoord_dt().rot), (marker1.FrameMoving.GetCoord().rot))))); } // q_8 = q''qqq + 2q'q'qq + 2q'qq'q + 2q'qqq' // + 2qq'q'q + 2qq'qq' + 2qqq'q' + qqqq'' temp2 = marker2.FrameMoving.GetCoord_dtdt().rot; if (ChQuaternion.Qnotnull(temp2)) { q_8 = ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord_dtdt().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord().rot), ChQuaternion.Qcross(Body1.GetCoord().rot, marker1.FrameMoving.GetCoord().rot))); // q_dtdt'm2 * q'o2 * q,o1 * q,m1 } else { //q_8 = ChQuaternion.QNULL; temp1 = marker1.FrameMoving.GetCoord_dtdt().rot; } if (ChQuaternion.Qnotnull(temp1)) { qtemp1 = ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord().rot), ChQuaternion.Qcross(Body1.GetCoord().rot, marker1.FrameMoving.GetCoord_dtdt().rot))); // q'm2 * q'o2 * q,o1 * q_dtdt,m1 q_8 = ChQuaternion.Qadd(q_8, qtemp1); } temp2 = marker2.FrameMoving.GetCoord_dt().rot; if (ChQuaternion.Qnotnull(temp2)) { qtemp1 = ChQuaternion.Qcross( ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord_dt().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord_dt().rot), ChQuaternion.Qcross(Body1.GetCoord().rot, marker1.FrameMoving.GetCoord().rot))); qtemp1 = ChQuaternion.Qscale(qtemp1, 2); // 2( q_dt'm2 * q_dt'o2 * q,o1 * q,m1) q_8 = ChQuaternion.Qadd(q_8, qtemp1); } temp2 = marker2.FrameMoving.GetCoord_dt().rot; if (ChQuaternion.Qnotnull(temp2)) { qtemp1 = ChQuaternion.Qcross( ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord_dt().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord().rot), ChQuaternion.Qcross(Body1.GetCoord_dt().rot, marker1.FrameMoving.GetCoord().rot))); qtemp1 = ChQuaternion.Qscale(qtemp1, 2); // 2( q_dt'm2 * q'o2 * q_dt,o1 * q,m1) q_8 = ChQuaternion.Qadd(q_8, qtemp1); } temp1 = marker1.FrameMoving.GetCoord_dt().rot; temp2 = marker2.FrameMoving.GetCoord_dt().rot; if (ChQuaternion.Qnotnull(temp2) && ChQuaternion.Qnotnull(temp1)) { qtemp1 = ChQuaternion.Qcross( ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord_dt().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord().rot), ChQuaternion.Qcross(Body1.GetCoord().rot, marker1.FrameMoving.GetCoord_dt().rot))); qtemp1 = ChQuaternion.Qscale(qtemp1, 2); // 2( q_dt'm2 * q'o2 * q,o1 * q_dt,m1) q_8 = ChQuaternion.Qadd(q_8, qtemp1); } qtemp1 = ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord_dt().rot), ChQuaternion.Qcross(Body1.GetCoord_dt().rot, marker1.FrameMoving.GetCoord().rot))); qtemp1 = ChQuaternion.Qscale(qtemp1, 2); // 2( q'm2 * q_dt'o2 * q_dt,o1 * q,m1) q_8 = ChQuaternion.Qadd(q_8, qtemp1); temp1 = marker1.FrameMoving.GetCoord_dt().rot; if (ChQuaternion.Qnotnull(temp1)) { qtemp1 = ChQuaternion.Qcross( ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord_dt().rot), ChQuaternion.Qcross(Body1.GetCoord().rot, marker1.FrameMoving.GetCoord_dt().rot))); qtemp1 = ChQuaternion.Qscale(qtemp1, 2); // 2( q'm2 * q_dt'o2 * q,o1 * q_dt,m1) q_8 = ChQuaternion.Qadd(q_8, qtemp1); } temp1 = marker1.FrameMoving.GetCoord_dt().rot; if (ChQuaternion.Qnotnull(temp1)) { qtemp1 = ChQuaternion.Qcross( ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord().rot), ChQuaternion.Qcross(Body1.GetCoord_dt().rot, marker1.FrameMoving.GetCoord_dt().rot))); qtemp1 = ChQuaternion.Qscale(qtemp1, 2); // 2( q'm2 * q'o2 * q_dt,o1 * q_dt,m1) q_8 = ChQuaternion.Qadd(q_8, qtemp1); } // q_4 = [Adtdt]'[A]'q + 2[Adt]'[Adt]'q // + 2[Adt]'[A]'qdt + 2[A]'[Adt]'qdt // ChMatrix33<double> m2_Rel_A_dt = new ChMatrix33<double>(0); marker2.FrameMoving.Compute_Adt(ref m2_Rel_A_dt); // ChMatrix33<double> m2_Rel_A_dtdt = new ChMatrix33<double>(0); marker2.FrameMoving.Compute_Adtdt(ref m2_Rel_A_dtdt); vtemp1 = Body2.GetA_dt().MatrT_x_Vect(PQw); vtemp2 = m2_Rel_A_dt.MatrT_x_Vect(vtemp1); q_4 = ChVector.Vmul(vtemp2, 2); // 2[Aq_dt]'[Ao2_dt]'*Qpq,w vtemp1 = Body2.GetA().MatrT_x_Vect(PQw_dt); vtemp2 = m2_Rel_A_dt.MatrT_x_Vect(vtemp1); vtemp2 = ChVector.Vmul(vtemp2, 2); // 2[Aq_dt]'[Ao2]'*Qpq,w_dt q_4 = ChVector.Vadd(q_4, vtemp2); vtemp1 = Body2.GetA_dt().MatrT_x_Vect(PQw_dt); vtemp2 = marker2.FrameMoving.GetA().MatrT_x_Vect(vtemp1); vtemp2 = ChVector.Vmul(vtemp2, 2); // 2[Aq]'[Ao2_dt]'*Qpq,w_dt q_4 = ChVector.Vadd(q_4, vtemp2); vtemp1 = Body2.GetA().MatrT_x_Vect(PQw); vtemp2 = m2_Rel_A_dtdt.MatrT_x_Vect(vtemp1); q_4 = ChVector.Vadd(q_4, vtemp2); // [Aq_dtdt]'[Ao2]'*Qpq,w // ----------- RELATIVE MARKER COORDINATES // relM.pos relM.pos = marker2.FrameMoving.GetA().MatrT_x_Vect(Body2.GetA().MatrT_x_Vect(PQw)); // relM.rot relM.rot = ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.GetBody().BodyFrame.GetCoord().rot), ChQuaternion.Qcross((marker1.GetBody().BodyFrame.GetCoord().rot), (marker1.FrameMoving.GetCoord().rot)))); // relM_dt.pos relM_dt.pos = ChVector.Vadd(ChVector.Vadd(m2_Rel_A_dt.MatrT_x_Vect(Body2.GetA().MatrT_x_Vect(PQw)), marker2.FrameMoving.GetA().MatrT_x_Vect(Body2.GetA_dt().MatrT_x_Vect(PQw))), marker2.FrameMoving.GetA().MatrT_x_Vect(Body2.GetA().MatrT_x_Vect(PQw_dt))); // relM_dt.rot relM_dt.rot = ChQuaternion.Qadd(q_AD, q_BC); // relM_dtdt.pos relM_dtdt.pos = ChVector.Vadd(ChVector.Vadd(marker2.FrameMoving.GetA().MatrT_x_Vect(Body2.GetA_dtdt().MatrT_x_Vect(PQw)), marker2.FrameMoving.GetA().MatrT_x_Vect(Body2.GetA().MatrT_x_Vect(PQw_dtdt))), q_4); // relM_dtdt.rot qtemp1 = ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord_dtdt().rot), ChQuaternion.Qcross(Body1.GetCoord().rot, marker1.FrameMoving.GetCoord().rot))); // ( q'm2 * q_dtdt'o2 * q,o1 * q,m1) relM_dtdt.rot = ChQuaternion.Qadd(q_8, qtemp1); qtemp1 = ChQuaternion.Qcross(ChQuaternion.Qconjugate(marker2.FrameMoving.GetCoord().rot), ChQuaternion.Qcross(ChQuaternion.Qconjugate(Body2.GetCoord().rot), ChQuaternion.Qcross(Body1.GetCoord_dtdt().rot, marker1.FrameMoving.GetCoord().rot))); // ( q'm2 * q'o2 * q_dtdt,o1 * q,m1) relM_dtdt.rot = ChQuaternion.Qadd(relM_dtdt.rot, qtemp1); // = q_8 + qq''qq + qqq''q // ... and also "user-friendly" relative coordinates: // relAngle and relAxis ChQuaternion.Q_to_AngAxis(relM.rot, ref relAngle, ref relAxis); // flip rel rotation axis if jerky sign if (relAxis.z < 0) { relAxis = ChVector.Vmul(relAxis, -1); relAngle = -relAngle; } // rotation axis relRotaxis = ChVector.Vmul(relAxis, relAngle); // relWvel ChFrame <double> .SetMatrix_Gw(ref relGw, relM.rot); // relGw.Set_Gw_matrix(relM.rot); relWvel = relGw.matrix.Matr34_x_Quat(relM_dt.rot); // relWacc relWacc = relGw.matrix.Matr34_x_Quat(relM_dtdt.rot); }
// Updates motion laws, marker positions, etc. public override void UpdateTime(double mytime) { // First, inherit to parent class base.UpdateTime(mytime); // Move markers 1 and 2 to align them as gear teeth ChMatrix33 <double> ma1 = new ChMatrix33 <double>(0); ChMatrix33 <double> ma2 = new ChMatrix33 <double>(0); ChMatrix33 <double> mrotma = new ChMatrix33 <double>(0); ChMatrix33 <double> marot_beta = new ChMatrix33 <double>(0); ChVector mx; ChVector my; ChVector mz; ChVector mr; ChVector mmark1; ChVector mmark2; ChVector lastX; ChVector vrota; ChCoordsys newmarkpos = new ChCoordsys(new ChVector(0, 0, 0), new ChQuaternion(1, 0, 0, 0)); ChFrame <double> abs_shaft1 = ChFrame <double> .FNULL; // new ChFrame<double>(); ChFrame <double> abs_shaft2 = ChFrame <double> .FNULL; //new ChFrame<double>(); ((ChFrame <double>)Body1).TransformLocalToParent(local_shaft1, abs_shaft1); ((ChFrame <double>)Body2).TransformLocalToParent(local_shaft2, abs_shaft2); ChVector vbdist = ChVector.Vsub(Get_shaft_pos1(), Get_shaft_pos2()); // ChVector Trad1 = ChVector.Vnorm(ChVector.Vcross(Get_shaft_dir1(), ChVector.Vnorm(ChVector.Vcross(Get_shaft_dir1(), vbdist)))); // ChVector Trad2 = ChVector.Vnorm(ChVector.Vcross(ChVector.Vnorm(ChVector.Vcross(Get_shaft_dir2(), vbdist)), Get_shaft_dir2())); double dist = ChVector.Vlength(vbdist); // compute actual rotation of the two wheels (relative to truss). ChVector md1 = abs_shaft1.GetA().MatrT_x_Vect(-vbdist); md1.z = 0; md1 = ChVector.Vnorm(md1); ChVector md2 = abs_shaft2.GetA().MatrT_x_Vect(-vbdist); md2.z = 0; md2 = ChVector.Vnorm(md2); double periodic_a1 = ChMaths.ChAtan2(md1.x, md1.y); double periodic_a2 = ChMaths.ChAtan2(md2.x, md2.y); double old_a1 = a1; double old_a2 = a2; double turns_a1 = Math.Floor(old_a1 / ChMaths.CH_C_2PI); double turns_a2 = Math.Floor(old_a2 / ChMaths.CH_C_2PI); double a1U = turns_a1 * ChMaths.CH_C_2PI + periodic_a1 + ChMaths.CH_C_2PI; double a1M = turns_a1 * ChMaths.CH_C_2PI + periodic_a1; double a1L = turns_a1 * ChMaths.CH_C_2PI + periodic_a1 - ChMaths.CH_C_2PI; a1 = a1M; if (Math.Abs(a1U - old_a1) < Math.Abs(a1M - old_a1)) { a1 = a1U; } if (Math.Abs(a1L - a1) < Math.Abs(a1M - a1)) { a1 = a1L; } double a2U = turns_a2 * ChMaths.CH_C_2PI + periodic_a2 + ChMaths.CH_C_2PI; double a2M = turns_a2 * ChMaths.CH_C_2PI + periodic_a2; double a2L = turns_a2 * ChMaths.CH_C_2PI + periodic_a2 - ChMaths.CH_C_2PI; a2 = a2M; if (Math.Abs(a2U - old_a2) < Math.Abs(a2M - old_a2)) { a2 = a2U; } if (Math.Abs(a2L - a2) < Math.Abs(a2M - a2)) { a2 = a2L; } // compute new markers coordsystem alignment my = ChVector.Vnorm(vbdist); mz = Get_shaft_dir1(); mx = ChVector.Vnorm(ChVector.Vcross(my, mz)); mr = ChVector.Vnorm(ChVector.Vcross(mz, mx)); mz = ChVector.Vnorm(ChVector.Vcross(mx, my)); ChVector mz2, mx2, mr2, my2; my2 = my; mz2 = Get_shaft_dir2(); mx2 = ChVector.Vnorm(ChVector.Vcross(my2, mz2)); mr2 = ChVector.Vnorm(ChVector.Vcross(mz2, mx2)); ma1.Set_A_axis(mx, my, mz); // rotate csys because of beta vrota.x = 0.0; vrota.y = beta; vrota.z = 0.0; mrotma.Set_A_Rxyz(vrota); marot_beta.nm.matrix.MatrMultiply(ma1.nm.matrix, mrotma.nm.matrix); // rotate csys because of alpha vrota.x = 0.0; vrota.y = 0.0; vrota.z = alpha; if (react_force.x < 0) { vrota.z = alpha; } else { vrota.z = -alpha; } mrotma.Set_A_Rxyz(vrota); ma1.nm.matrix.MatrMultiply(marot_beta.nm.matrix, mrotma.nm.matrix); ma2.nm.matrix.CopyFromMatrix(ma1.nm.matrix); // is a bevel gear? double be = Math.Acos(ChVector.Vdot(Get_shaft_dir1(), Get_shaft_dir2())); bool is_bevel = true; if (Math.Abs(ChVector.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 = ChVector.Vdot(mr, vbdist); double inv_tau = 1.0 / tau; if (!epicyclic) { r2 = pardist - pardist / (inv_tau + 1.0); } else { r2 = pardist - (tau * pardist) / (tau - 1.0); } r1 = r2 * tau; } else { double gamma2; if (!epicyclic) { gamma2 = be / (tau + 1.0); } else { gamma2 = be / (-tau + 1.0); } double al = ChMaths.CH_C_PI - Math.Acos(ChVector.Vdot(Get_shaft_dir2(), my)); double te = ChMaths.CH_C_PI - al - be; double fd = Math.Sin(te) * (dist / Math.Sin(be)); r2 = fd * Math.Tan(gamma2); r1 = r2 * tau; } // compute markers positions, supposing they // stay on the ideal wheel contact point mmark1 = ChVector.Vadd(Get_shaft_pos2(), ChVector.Vmul(mr2, r2)); mmark2 = mmark1; contact_pt = mmark1; // correct marker 1 position if phasing is not correct if (checkphase) { double realtau = tau; if (epicyclic) { realtau = -tau; } double m_delta; m_delta = -(a2 / realtau) - a1 - phase; if (m_delta > ChMaths.CH_C_PI) { m_delta -= (ChMaths.CH_C_2PI); // range -180..+180 is better than 0...360 } if (m_delta > (ChMaths.CH_C_PI / 4.0)) { m_delta = (ChMaths.CH_C_PI / 4.0); // phase correction only in +/- 45° } if (m_delta < -(ChMaths.CH_C_PI / 4.0)) { m_delta = -(ChMaths.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(ChVector.Vsub(mmark1, Get_shaft_pos1())); mmark1 = mrotma.Matr_x_Vect(mmark1); mmark1 = ChVector.Vadd(abs_shaft1.GetA().Matr_x_Vect(mmark1), Get_shaft_pos1()); } // Move Shaft 1 along its direction if not aligned to wheel double offset = ChVector.Vdot(Get_shaft_dir1(), (contact_pt - Get_shaft_pos1())); ChVector moff = Get_shaft_dir1() * offset; if (Math.Abs(offset) > 0.0001) { local_shaft1.SetPos(local_shaft1.GetPos() + Body1.TransformDirectionParentToLocal(moff)); } // ! Require that the BDF routine of marker won't handle speed and acc.calculus of the moved marker 2! marker2.SetMotionType(ChMarker.eChMarkerMotion.M_MOTION_EXTERNAL); marker1.SetMotionType(ChMarker.eChMarkerMotion.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 = ChVector.VNULL; deltaC_dt.pos = ChVector.VNULL; deltaC_dtdt.pos = ChVector.VNULL; deltaC.rot = ChQuaternion.QUNIT; // no relative rotations imposed! deltaC_dt.rot = ChQuaternion.QNULL; deltaC_dtdt.rot = ChQuaternion.QNULL; }