void CartesianPositionController::update()
{
for (unsigned int i = 0; i < effort_.joints_.size(); ++i)
{
if (!effort_.joints_[i]->calibrated_)
return;
}
if (reset_) {
reset_ = false;
getTipPosition(&command_);
}
assert(tip_);
double time = robot_->hw_->current_time_;
btVector3 error = command_ - (tip_->abs_position_ + effort_.offset_);
effort_.command_[0] = -pid_x_.updatePid(error.x(), time - last_time_);
effort_.command_[1] = -pid_y_.updatePid(error.y(), time - last_time_);
effort_.command_[2] = -pid_z_.updatePid(error.z(), time - last_time_);
effort_.update();
last_time_ = time;
}
void Hook::getTipGlobalPosition(State* s, double* out)
{
// The hook tip in local coordinates.
float pos_tip[3];
getTipPosition(pos_tip);
// The hook tip in global coordinates.
s->posLocalToGlobal(pos_tip, out);
}
void FingerData::updateTrail() {
if (_tipTrailPositions.size() == 0)
return;
if (_isActive) {
// Add the next point in the trail.
_tipTrailCurrentStartIndex--;
if (_tipTrailCurrentStartIndex < 0)
_tipTrailCurrentStartIndex = _tipTrailPositions.size() - 1;
_tipTrailPositions[_tipTrailCurrentStartIndex] = getTipPosition();
if (_tipTrailCurrentValidLength < (int)_tipTrailPositions.size())
_tipTrailCurrentValidLength++;
}
else {
// It's not active, so just kill the trail.
_tipTrailCurrentValidLength = 0;
}
}
void Hook::calcForce(Ground* g_cb, RigidBody* body, State* s, float* lv, float* lrot)
{
// Init the return values
int i;
for(i=0; i<3; i++) _force[i] = 0;
// Don't bother if it's fully retracted
if(_extension <= 0)
return;
// For the first guess, the position fraction is equal to the
// extension value.
_frac = _extension;
// The ground plane transformed to the local frame.
float ground[4];
s->planeGlobalToLocal(_global_ground, ground);
// The hook tip in local coordinates.
float ltip[3];
getTipPosition(ltip);
// Correct the extension value for no intersection.
// Check if the tip will intersect the ground or not. That is, compute
// the distance of the tip to the ground plane.
float tipdist = ground[3] - Math::dot3(ltip, ground);
if(0 <= tipdist) {
_frac = _extension;
} else {
// Compute the distance of the hooks mount point from the ground plane.
float mountdist = ground[3] - Math::dot3(_pos, ground);
// Compute the distance of the hooks mount point from the ground plane
// in the x-z plane. It holds:
// mountdist = mountdist_xz*cos(angle(normal_yz, e_z))
// thus
float mountdist_xz = _length;
if (ground[2] != 0) {
float nrm_yz = Math::sqrt(ground[1]*ground[1]+ground[2]*ground[2]);
mountdist_xz = -mountdist*nrm_yz/ground[2];
}
if (mountdist_xz < _length) {
float ang = Math::asin(mountdist_xz/_length)
+ Math::atan2(ground[2], ground[0]) + YASIM_PI2;
_frac = (ang - _up_ang)/(_down_ang - _up_ang);
} else {
_frac = _extension;
}
}
double hook_area[4][3];
// The hook mount in global coordinates.
s->posLocalToGlobal(_pos, hook_area[1]);
// Recompute the hook tip in global coordinates.
getTipGlobalPosition(s, hook_area[0]);
// The old positions.
hook_area[2][0] = _old_mount[0];
hook_area[2][1] = _old_mount[1];
hook_area[2][2] = _old_mount[2];
hook_area[3][0] = _old_tip[0];
hook_area[3][1] = _old_tip[1];
hook_area[3][2] = _old_tip[2];
// Check if we caught a wire.
// Returns true if we caught one.
if (!_has_wire && g_cb->caughtWire(hook_area))
_has_wire = true;
// save actual position as old position ...
_old_mount[0] = hook_area[1][0];
_old_mount[1] = hook_area[1][1];
_old_mount[2] = hook_area[1][2];
_old_tip[0] = hook_area[0][0];
_old_tip[1] = hook_area[0][1];
_old_tip[2] = hook_area[0][2];
if (!_has_wire)
return;
// Get the wire endpoints and their velocities wrt the earth.
double dpos[2][3];
float wire_vel[2][3];
g_cb->getWire(dpos, wire_vel);
// Transform those to the local coordinate system
float wire_lpos[2][3];
s->posGlobalToLocal(dpos[0], wire_lpos[0]);
s->posGlobalToLocal(dpos[1], wire_lpos[1]);
s->velGlobalToLocal(wire_vel[0], wire_vel[0]);
s->velGlobalToLocal(wire_vel[1], wire_vel[1]);
// Compute the velocity of the hooks mount point in the local frame.
float mount_vel[3];
body->pointVelocity(_pos, lrot, mount_vel);
Math::add3(lv, mount_vel, mount_vel);
// The velocity of the hook mount point wrt the earth in
// the local frame.
float v_wrt_we[2][3];
Math::sub3(mount_vel, wire_vel[0], v_wrt_we[0]);
Math::sub3(mount_vel, wire_vel[1], v_wrt_we[1]);
float f[2][3];
// The vector from the wire ends to the hook mount point.
Math::sub3(_pos, wire_lpos[0], f[0]);
Math::sub3(_pos, wire_lpos[1], f[1]);
// We only need the direction.
float mf0 = Math::mag3(f[0]);
float mf1 = Math::mag3(f[1]);
Math::mul3(1.0/mf0, f[0], f[0]);
Math::mul3(1.0/mf1, f[1], f[1]);
// The velocity of the wire wrt the wire ends at the wire
// mount points.
float v0 = Math::dot3(v_wrt_we[0], f[0]);
float v1 = Math::dot3(v_wrt_we[1], f[1]);
// We assume that the wire slips through the hook. So the velocity
// will be equal at both sides. So take the mean of both.
float v = 0.5*(v0+v1);
// Release wire when we reach zero velocity.
if (v <= 0.0) {
_has_wire = false;
g_cb->releaseWire();
return;
}
// The trick is to multiply with the current mass of the aircraft.
// That way we control the acceleration and not the force. This is
// the implicit calibration of the wires for aircrafts of
// different mass.
float mass = body->getTotalMass();
// The local force is the vector sum of the force on each wire.
// The force is computed with some constant tension on the wires
// (80000N) plus a velocity dependent component.
Math::add3(f[0], f[1], _force);
Math::mul3(-mass*( 1.0 + ((mf0+mf1)/70) + 0.2*v ), _force, _force);
// Now in the body coordinate system, eliminate the Y coord part
// of the hook force. Physically this means that the wire will just
// slip through the hook instead of applying a side force.
_force[1] = 0.0;
}
