195 lines
6.7 KiB
C++
195 lines
6.7 KiB
C++
// UFO.cxx -- interface to the "UFO" flight model
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//
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// Written by Curtis Olson, started October 1999.
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// Slightly modified from MagicCarpet.cxx by Jonathan Polley, April 2002
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//
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// Copyright (C) 1999-2002 Curtis L. Olson - http://www.flightgear.org/~curt
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <simgear/math/sg_geodesy.hxx>
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#include <simgear/math/point3d.hxx>
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#include <simgear/math/polar3d.hxx>
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#include <Aircraft/controls.hxx>
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#include <Main/globals.hxx>
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#include <Main/fg_props.hxx>
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#include "UFO.hxx"
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FGUFO::FGUFO( double dt ) :
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Throttle(new lowpass(fgGetDouble("/controls/damping/throttle", 0.3))),
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Aileron(new lowpass(fgGetDouble("/controls/damping/aileron", 0.65))),
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Elevator(new lowpass(fgGetDouble("/controls/damping/elevator", 0.65))),
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Rudder(new lowpass(fgGetDouble("/controls/damping/rudder", 0.05))),
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Aileron_Trim(new lowpass(fgGetDouble("/controls/damping/aileron-trim", 0.65))),
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Elevator_Trim(new lowpass(fgGetDouble("/controls/damping/elevator-trim", 0.65))),
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Rudder_Trim(new lowpass(fgGetDouble("/controls/damping/rudder-trim", 0.05))),
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Speed_Max(fgGetNode("/engines/engine/speed-max-mps", true))
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{
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}
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FGUFO::~FGUFO() {
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delete Throttle;
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delete Aileron;
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delete Elevator;
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delete Rudder;
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delete Aileron_Trim;
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delete Elevator_Trim;
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delete Rudder_Trim;
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}
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// Initialize the UFO flight model, dt is the time increment
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// for each subsequent iteration through the EOM
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void FGUFO::init() {
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common_init();
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if (Speed_Max->getDoubleValue() < 0.01)
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Speed_Max->setDoubleValue(2000.0);
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}
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// Run an iteration of the EOM (equations of motion)
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void FGUFO::update( double dt ) {
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// cout << "FGLaRCsim::update()" << endl;
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if (is_suspended())
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return;
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double time_step = dt;
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// read the throttle
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double throttle = globals->get_controls()->get_throttle( 0 );
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double brake_left = globals->get_controls()->get_brake_left();
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double brake_right = globals->get_controls()->get_brake_right();
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if (brake_left > 0.5 || brake_right > 0.5)
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throttle = -throttle;
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throttle = Throttle->filter(dt, throttle);
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// read and lowpass-filter the state of the control surfaces
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double aileron = Aileron->filter(dt, globals->get_controls()->get_aileron());
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double elevator = Elevator->filter(dt, globals->get_controls()->get_elevator());
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double rudder = Rudder->filter(dt, globals->get_controls()->get_rudder());
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aileron += Aileron_Trim->filter(dt, globals->get_controls()->get_aileron_trim());
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elevator += Elevator_Trim->filter(dt, globals->get_controls()->get_elevator_trim());
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rudder += Rudder_Trim->filter(dt, globals->get_controls()->get_rudder_trim());
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double velocity = throttle * Speed_Max->getDoubleValue(); // meters/sec
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double old_pitch = get_Theta();
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double pitch_rate = SGD_PI_4; // assume I will be pitching up
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double target_pitch = -elevator * SGD_PI_2;
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if (old_pitch > target_pitch) // pitching down
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pitch_rate *= -1;
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double pitch = old_pitch + (pitch_rate * time_step);
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if (pitch_rate > 0.0) { // pitching up
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if (pitch > target_pitch)
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pitch = target_pitch;
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} else if (pitch_rate < 0.0) { // pitching down
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if (pitch < target_pitch)
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pitch = target_pitch;
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}
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double old_roll = get_Phi();
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double roll_rate = SGD_PI_4;
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double target_roll = aileron * SGD_PI_2;
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if (old_roll > target_roll)
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roll_rate *= -1;
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double roll = old_roll + (roll_rate * time_step);
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if (roll_rate > 0.0) { // rolling CW
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if (roll > target_roll)
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roll = target_roll;
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} else if (roll_rate < 0.0) { // rolling CCW
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if (roll < target_roll)
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roll = target_roll;
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}
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// the vertical speed of the aircraft
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double real_climb_rate = sin (pitch) * SG_METER_TO_FEET * velocity; // feet/sec
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_set_Climb_Rate( -elevator * 10.0 );
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double climb = real_climb_rate * time_step;
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// the lateral speed of the aircraft
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double speed = cos (pitch) * velocity; // meters/sec
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double dist = speed * time_step;
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double kts = velocity * SG_METER_TO_NM * 3600.0;
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_set_V_equiv_kts( kts );
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_set_V_calibrated_kts( kts );
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_set_V_ground_speed( kts );
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// angle of turn
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double turn_rate = sin(roll) * SGD_PI_4; // radians/sec
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double turn = turn_rate * time_step;
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double yaw = fabs(rudder) < .2 ? 0.0 : rudder / (25 + fabs(speed) * .1);
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// update (lon/lat) position
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double lat2, lon2, az2;
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if ( fabs(speed) > SG_EPSILON ) {
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geo_direct_wgs_84 ( get_Altitude(),
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get_Latitude() * SGD_RADIANS_TO_DEGREES,
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get_Longitude() * SGD_RADIANS_TO_DEGREES,
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get_Psi() * SGD_RADIANS_TO_DEGREES,
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dist, &lat2, &lon2, &az2 );
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_set_Longitude( lon2 * SGD_DEGREES_TO_RADIANS );
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_set_Latitude( lat2 * SGD_DEGREES_TO_RADIANS );
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}
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// cout << "lon error = " << fabs(end.x()*SGD_RADIANS_TO_DEGREES - lon2)
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// << " lat error = " << fabs(end.y()*SGD_RADIANS_TO_DEGREES - lat2)
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// << endl;
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double sl_radius, lat_geoc;
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sgGeodToGeoc( get_Latitude(), get_Altitude(), &sl_radius, &lat_geoc );
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// update euler angles
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double heading = fmod(get_Psi() + turn + yaw, SGD_2PI);
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_set_Euler_Angles(roll, pitch, heading);
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_set_Euler_Rates(0,0,0);
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_set_Geocentric_Position( lat_geoc, get_Longitude(),
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sl_radius + get_Altitude() + climb );
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// cout << "sea level radius (ft) = " << sl_radius << endl;
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// cout << "(setto) sea level radius (ft) = " << get_Sea_level_radius() << endl;
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_update_ground_elev_at_pos();
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_set_Sea_level_radius( sl_radius * SG_METER_TO_FEET);
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_set_Altitude( get_Altitude() + climb );
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_set_Altitude_AGL( get_Altitude() - get_Runway_altitude() );
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set_V_north(cos(heading) * velocity * SG_METER_TO_FEET);
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set_V_east(sin(heading) * velocity * SG_METER_TO_FEET);
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set_V_down(-real_climb_rate);
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}
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