ardupilot/ArduCopter/takeoff.cpp

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
#include "Copter.h"
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// This file contains the high-level takeoff logic for Loiter, PosHold, AltHold, Sport modes.
// The take-off can be initiated from a GCS NAV_TAKEOFF command which includes a takeoff altitude
// A safe takeoff speed is calculated and used to calculate a time_ms
// the pos_control target is then slowly increased until time_ms expires
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// return true if this flight mode supports user takeoff
// must_nagivate is true if mode must also control horizontal position
bool Copter::current_mode_has_user_takeoff(bool must_navigate)
{
switch (control_mode) {
case GUIDED:
case LOITER:
case POSHOLD:
return true;
case ALT_HOLD:
case SPORT:
return !must_navigate;
default:
return false;
}
}
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// initiate user takeoff - called when MAVLink TAKEOFF command is received
bool Copter::do_user_takeoff(float takeoff_alt_cm, bool must_navigate)
{
if (motors.armed() && ap.land_complete && current_mode_has_user_takeoff(must_navigate) && takeoff_alt_cm > current_loc.alt) {
#if FRAME_CONFIG == HELI_FRAME
// Helicopters should return false if MAVlink takeoff command is received while the rotor is not spinning
if (!motors.rotor_runup_complete()) {
return false;
}
#endif
switch(control_mode) {
case GUIDED:
if (guided_takeoff_start(takeoff_alt_cm)) {
set_auto_armed(true);
return true;
}
return false;
case LOITER:
case POSHOLD:
case ALT_HOLD:
case SPORT:
set_auto_armed(true);
takeoff_timer_start(takeoff_alt_cm);
return true;
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default:
return false;
}
}
return false;
}
// start takeoff to specified altitude above home in centimeters
void Copter::takeoff_timer_start(float alt_cm)
{
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// calculate climb rate
float speed = MIN(wp_nav.get_speed_up(), MAX(g.pilot_velocity_z_max*2.0f/3.0f, g.pilot_velocity_z_max-50.0f));
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// sanity check speed and target
if (takeoff_state.running || speed <= 0.0f || alt_cm <= 0.0f) {
return;
}
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// initialise takeoff state
takeoff_state.running = true;
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takeoff_state.max_speed = speed;
takeoff_state.start_ms = millis();
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takeoff_state.alt_delta = alt_cm;
}
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// stop takeoff
void Copter::takeoff_stop()
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{
takeoff_state.running = false;
takeoff_state.start_ms = 0;
}
// returns pilot and takeoff climb rates
// pilot_climb_rate is both an input and an output
// takeoff_climb_rate is only an output
// has side-effect of turning takeoff off when timeout as expired
void Copter::takeoff_get_climb_rates(float& pilot_climb_rate, float& takeoff_climb_rate)
{
// return pilot_climb_rate if take-off inactive
if (!takeoff_state.running) {
takeoff_climb_rate = 0.0f;
return;
}
// acceleration of 50cm/s/s
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static const float takeoff_accel = 50.0f;
float takeoff_minspeed = MIN(50.0f,takeoff_state.max_speed);
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float time_elapsed = (millis()-takeoff_state.start_ms)*1.0e-3f;
float speed = MIN(time_elapsed*takeoff_accel+takeoff_minspeed, takeoff_state.max_speed);
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float time_to_max_speed = (takeoff_state.max_speed-takeoff_minspeed)/takeoff_accel;
float height_gained;
if (time_elapsed <= time_to_max_speed) {
height_gained = 0.5f*takeoff_accel*sq(time_elapsed) + takeoff_minspeed*time_elapsed;
} else {
height_gained = 0.5f*takeoff_accel*sq(time_to_max_speed) + takeoff_minspeed*time_to_max_speed +
(time_elapsed-time_to_max_speed)*takeoff_state.max_speed;
}
// check if the takeoff is over
if (height_gained >= takeoff_state.alt_delta) {
takeoff_stop();
}
// if takeoff climb rate is zero return
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if (speed <= 0.0f) {
takeoff_climb_rate = 0.0f;
return;
}
// default take-off climb rate to maximum speed
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takeoff_climb_rate = speed;
// if pilot's commands descent
if (pilot_climb_rate < 0.0f) {
// if overall climb rate is still positive, move to take-off climb rate
if (takeoff_climb_rate + pilot_climb_rate > 0.0f) {
takeoff_climb_rate = takeoff_climb_rate + pilot_climb_rate;
pilot_climb_rate = 0;
} else {
// if overall is negative, move to pilot climb rate
pilot_climb_rate = pilot_climb_rate + takeoff_climb_rate;
takeoff_climb_rate = 0.0f;
}
} else { // pilot commands climb
// pilot climb rate is zero until it surpasses the take-off climb rate
if (pilot_climb_rate > takeoff_climb_rate) {
pilot_climb_rate = pilot_climb_rate - takeoff_climb_rate;
} else {
pilot_climb_rate = 0.0f;
}
}
}