// UFO.cxx -- interface to the "UFO" flight model
//
// Written by Curtis Olson, started October 1999.
// Slightly modified from MagicCarpet.cxx by Jonathan Polley, April 2002
//
// Copyright (C) 1999-2002 Curtis L. Olson - http://www.flightgear.org/~curt
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <simgear/math/sg_geodesy.hxx>
#include <Aircraft/controls.hxx>
#include <Main/globals.hxx>
#include <Main/fg_props.hxx>
#include "UFO.hxx"
double FGUFO::lowpass::_dt;
FGUFO::FGUFO( double dt ) :
Throttle(new lowpass(fgGetDouble("/controls/damping/throttle", 0.1))),
Aileron(new lowpass(fgGetDouble("/controls/damping/aileron", 0.65))),
Elevator(new lowpass(fgGetDouble("/controls/damping/elevator", 0.65))),
Rudder(new lowpass(fgGetDouble("/controls/damping/rudder", 0.05))),
Aileron_Trim(new lowpass(fgGetDouble("/controls/damping/aileron-trim", 0.65))),
Elevator_Trim(new lowpass(fgGetDouble("/controls/damping/elevator-trim", 0.65))),
Rudder_Trim(new lowpass(fgGetDouble("/controls/damping/rudder-trim", 0.05))),
Speed_Max(fgGetNode("/engines/engine/speed-max-mps", true))
{
}
FGUFO::~FGUFO() {
delete Throttle;
delete Aileron;
delete Elevator;
delete Rudder;
delete Aileron_Trim;
delete Elevator_Trim;
delete Rudder_Trim;
}
// Initialize the UFO flight model, dt is the time increment
// for each subsequent iteration through the EOM
void FGUFO::init() {
common_init();
if (Speed_Max->getDoubleValue() < 0.01)
Speed_Max->setDoubleValue(2000.0);
}
// Run an iteration of the EOM (equations of motion)
void FGUFO::update( double dt ) {
if (is_suspended())
return;
lowpass::set_delta(dt);
double time_step = dt;
FGControls *ctrl = globals->get_controls();
// read the throttle
double throttle = ctrl->get_throttle( 0 );
double brake_left = ctrl->get_brake_left();
double brake_right = ctrl->get_brake_right();
if (brake_left > 0.5 || brake_right > 0.5)
throttle = -throttle;
double velocity = Throttle->filter(throttle) * Speed_Max->getDoubleValue(); // meters/sec
// read and lowpass-filter the state of the control surfaces
double aileron = Aileron->filter(ctrl->get_aileron());
double elevator = Elevator->filter(ctrl->get_elevator());
double rudder = Rudder->filter(ctrl->get_rudder());
aileron += Aileron_Trim->filter(ctrl->get_aileron_trim());
elevator += Elevator_Trim->filter(ctrl->get_elevator_trim());
rudder += Rudder_Trim->filter(ctrl->get_rudder_trim());
double old_pitch = get_Theta();
double pitch_rate = SGD_PI_4; // assume I will be pitching up
double target_pitch = -elevator * SGD_PI_2;
if (old_pitch > target_pitch) // pitching down
pitch_rate *= -1;
double pitch = old_pitch + (pitch_rate * time_step);
if (pitch_rate > 0.0) { // pitching up
if (pitch > target_pitch)
pitch = target_pitch;
} else if (pitch_rate < 0.0) { // pitching down
if (pitch < target_pitch)
pitch = target_pitch;
}
double old_roll = get_Phi();
double roll_rate = SGD_PI_4;
double target_roll = aileron * SGD_PI_2;
if (old_roll > target_roll)
roll_rate *= -1;
double roll = old_roll + (roll_rate * time_step);
if (roll_rate > 0.0) { // rolling CW
if (roll > target_roll)
roll = target_roll;
} else if (roll_rate < 0.0) { // rolling CCW
if (roll < target_roll)
roll = target_roll;
}
// the vertical speed of the aircraft
double real_climb_rate = sin (pitch) * SG_METER_TO_FEET * velocity; // feet/sec
_set_Climb_Rate( -elevator * 10.0 );
double climb = real_climb_rate * time_step;
// the lateral speed of the aircraft
double speed = cos (pitch) * velocity; // meters/sec
double dist = speed * time_step;
double kts = velocity * SG_METER_TO_NM * 3600.0;
_set_V_equiv_kts( kts );
_set_V_calibrated_kts( kts );
set_V_ground_speed_kt( kts );
// angle of turn
double turn_rate = sin(roll) * SGD_PI_4; // radians/sec
double turn = turn_rate * time_step;
double yaw = fabs(rudder) < .05 ? 0.0 : (rudder * (fabs(rudder) - 0.05) / 10);
// update (lon/lat) position
double lat2 = 0.0, lon2 = 0.0, az2 = 0.0;
if ( fabs(speed) > SG_EPSILON ) {
geo_direct_wgs_84 ( get_Altitude(),
get_Latitude() * SGD_RADIANS_TO_DEGREES,
get_Longitude() * SGD_RADIANS_TO_DEGREES,
get_Psi() * SGD_RADIANS_TO_DEGREES,
dist, &lat2, &lon2, &az2 );
_set_Geodetic_Position( lat2 * SGD_DEGREES_TO_RADIANS, lon2 * SGD_DEGREES_TO_RADIANS );
}
// cout << "lon error = " << fabs(end.x()*SGD_RADIANS_TO_DEGREES - lon2)
// << " lat error = " << fabs(end.y()*SGD_RADIANS_TO_DEGREES - lat2)
// << endl;
double sl_radius, lat_geoc;
sgGeodToGeoc( get_Latitude(), get_Altitude(), &sl_radius, &lat_geoc );
// update euler angles
double heading = SGMiscd::normalizePeriodic(0, SGD_2PI, get_Psi() + turn + yaw );
_set_Euler_Angles(roll, pitch, heading);
_set_Euler_Rates(0,0,0);
_set_Geocentric_Position( lat_geoc, get_Longitude(),
sl_radius + get_Altitude() + climb );
// cout << "sea level radius (ft) = " << sl_radius << endl;
// cout << "(setto) sea level radius (ft) = " << get_Sea_level_radius() << endl;
_update_ground_elev_at_pos();
_set_Sea_level_radius( sl_radius * SG_METER_TO_FEET);
_set_Altitude( get_Altitude() + climb );
_set_Altitude_AGL( get_Altitude() - get_Runway_altitude() );
set_V_north(cos(heading) * velocity * SG_METER_TO_FEET);
set_V_east(sin(heading) * velocity * SG_METER_TO_FEET);
set_V_down(-real_climb_rate);
}