ardupilot/ArduPlane/takeoff.cpp

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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#include "Plane.h"
/* Check for automatic takeoff conditions being met using the following sequence:
* 1) Check for adequate GPS lock - if not return false
* 2) Check the gravity compensated longitudinal acceleration against the threshold and start the timer if true
* 3) Wait until the timer has reached the specified value (increments of 0.1 sec) and then check the GPS speed against the threshold
* 4) If the GPS speed is above the threshold and the attitude is within limits then return true and reset the timer
* 5) If the GPS speed and attitude within limits has not been achieved after 2.5 seconds, return false and reset the timer
* 6) If the time lapsed since the last timecheck is greater than 0.2 seconds, return false and reset the timer
* NOTE : This function relies on the TECS 50Hz processing for its acceleration measure.
*/
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bool Plane::auto_takeoff_check(void)
{
// this is a more advanced check that relies on TECS
uint32_t now = millis();
uint16_t wait_time_ms = MIN(uint16_t(g.takeoff_throttle_delay)*100,12700);
// Reset states if process has been interrupted
if (takeoff_state.last_check_ms && (now - takeoff_state.last_check_ms) > 200) {
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gcs_send_text_fmt(MAV_SEVERITY_WARNING, "Timer interrupted AUTO");
takeoff_state.launchTimerStarted = false;
takeoff_state.last_tkoff_arm_time = 0;
takeoff_state.last_check_ms = now;
return false;
}
takeoff_state.last_check_ms = now;
// Check for bad GPS
if (gps.status() < AP_GPS::GPS_OK_FIX_3D) {
// no auto takeoff without GPS lock
return false;
}
// Check for launch acceleration or timer started. NOTE: relies on TECS 50Hz processing
if (!takeoff_state.launchTimerStarted &&
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!is_zero(g.takeoff_throttle_min_accel) &&
SpdHgt_Controller->get_VXdot() < g.takeoff_throttle_min_accel) {
goto no_launch;
}
// we've reached the acceleration threshold, so start the timer
if (!takeoff_state.launchTimerStarted) {
takeoff_state.launchTimerStarted = true;
takeoff_state.last_tkoff_arm_time = now;
if (now - takeoff_state.last_report_ms > 2000) {
gcs_send_text_fmt(MAV_SEVERITY_INFO, "Armed AUTO, xaccel = %.1f m/s/s, waiting %.1f sec",
(double)SpdHgt_Controller->get_VXdot(), (double)(wait_time_ms*0.001f));
takeoff_state.last_report_ms = now;
}
}
// Only perform velocity check if not timed out
if ((now - takeoff_state.last_tkoff_arm_time) > wait_time_ms+100U) {
if (now - takeoff_state.last_report_ms > 2000) {
gcs_send_text_fmt(MAV_SEVERITY_WARNING, "Timeout AUTO");
takeoff_state.last_report_ms = now;
}
goto no_launch;
}
// Check aircraft attitude for bad launch
if (ahrs.pitch_sensor <= -3000 ||
ahrs.pitch_sensor >= 4500 ||
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labs(ahrs.roll_sensor) > 3000) {
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gcs_send_text_fmt(MAV_SEVERITY_WARNING, "Bad launch AUTO");
goto no_launch;
}
// Check ground speed and time delay
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if (((gps.ground_speed() > g.takeoff_throttle_min_speed || is_zero(g.takeoff_throttle_min_speed))) &&
((now - takeoff_state.last_tkoff_arm_time) >= wait_time_ms)) {
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gcs_send_text_fmt(MAV_SEVERITY_INFO, "Triggered AUTO. GPS speed = %.1f", (double)gps.ground_speed());
takeoff_state.launchTimerStarted = false;
takeoff_state.last_tkoff_arm_time = 0;
steer_state.locked_course_err = 0; // use current heading without any error offset
return true;
}
// we're not launching yet, but the timer is still going
return false;
no_launch:
takeoff_state.launchTimerStarted = false;
takeoff_state.last_tkoff_arm_time = 0;
return false;
}
/*
calculate desired bank angle during takeoff, setting nav_roll_cd
*/
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void Plane::takeoff_calc_roll(void)
{
if (steer_state.hold_course_cd == -1) {
// we don't yet have a heading to hold - just level
// the wings until we get up enough speed to get a GPS heading
nav_roll_cd = 0;
return;
}
calc_nav_roll();
// during takeoff use the level flight roll limit to prevent large
// wing strike. Slowly allow for more roll as we get higher above
// the takeoff altitude
float roll_limit = roll_limit_cd*0.01f;
float baro_alt = barometer.get_altitude();
// below 5m use the LEVEL_ROLL_LIMIT
const float lim1 = 5;
// at 15m allow for full roll
const float lim2 = 15;
if (baro_alt < auto_state.baro_takeoff_alt+lim1) {
roll_limit = g.level_roll_limit;
} else if (baro_alt < auto_state.baro_takeoff_alt+lim2) {
float proportion = (baro_alt - (auto_state.baro_takeoff_alt+lim1)) / (lim2 - lim1);
roll_limit = (1-proportion) * g.level_roll_limit + proportion * roll_limit;
}
nav_roll_cd = constrain_int32(nav_roll_cd, -roll_limit*100UL, roll_limit*100UL);
}
/*
calculate desired pitch angle during takeoff, setting nav_pitch_cd
*/
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void Plane::takeoff_calc_pitch(void)
{
if (auto_state.highest_airspeed < g.takeoff_rotate_speed) {
// we have not reached rotate speed, use a target pitch of 5
// degrees. This should be enough to get the tail off the
// ground, while making it unlikely that overshoot in the
// pitch controller will cause a prop strike
nav_pitch_cd = 500;
return;
}
if (ahrs.airspeed_sensor_enabled()) {
int16_t takeoff_pitch_min_cd = get_takeoff_pitch_min_cd();
calc_nav_pitch();
if (nav_pitch_cd < takeoff_pitch_min_cd) {
nav_pitch_cd = takeoff_pitch_min_cd;
}
} else {
nav_pitch_cd = ((gps.ground_speed()*100) / (float)g.airspeed_cruise_cm) * auto_state.takeoff_pitch_cd;
nav_pitch_cd = constrain_int32(nav_pitch_cd, 500, auto_state.takeoff_pitch_cd);
}
}
/*
* get the pitch min used during takeoff. This matches the mission pitch until near the end where it allows it to levels off
*/
int16_t Plane::get_takeoff_pitch_min_cd(void)
{
if (flight_stage != AP_SpdHgtControl::FLIGHT_TAKEOFF) {
return auto_state.takeoff_pitch_cd;
}
int32_t relative_alt_cm = adjusted_relative_altitude_cm();
int32_t remaining_height_to_target_cm = (auto_state.takeoff_altitude_rel_cm - relative_alt_cm);
// seconds to target alt method
if (g.takeoff_pitch_limit_reduction_sec > 0) {
// if height-below-target has been initialized then use it to create and apply a scaler to the pitch_min
if (auto_state.height_below_takeoff_to_level_off_cm != 0) {
float scalar = remaining_height_to_target_cm / (float)auto_state.height_below_takeoff_to_level_off_cm;
return auto_state.takeoff_pitch_cd * scalar;
}
// are we entering the region where we want to start leveling off before we reach takeoff alt?
if (auto_state.sink_rate < -0.1f) {
float sec_to_target = (remaining_height_to_target_cm * 0.01f) / (-auto_state.sink_rate);
if (sec_to_target > 0 &&
relative_alt_cm >= 1000 &&
sec_to_target <= g.takeoff_pitch_limit_reduction_sec) {
// make a note of that altitude to use it as a start height for scaling
gcs_send_text_fmt(MAV_SEVERITY_INFO, "Takeoff level-off starting at %dm", remaining_height_to_target_cm/100);
auto_state.height_below_takeoff_to_level_off_cm = remaining_height_to_target_cm;
}
}
}
return auto_state.takeoff_pitch_cd;
}
/*
return a tail hold percentage during initial takeoff for a tail
dragger
This can be used either in auto-takeoff or in FBWA mode with
FBWA_TDRAG_CHAN enabled
*/
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int8_t Plane::takeoff_tail_hold(void)
{
bool in_takeoff = ((control_mode == AUTO && !auto_state.takeoff_complete) ||
(control_mode == FLY_BY_WIRE_A && auto_state.fbwa_tdrag_takeoff_mode));
if (!in_takeoff) {
// not in takeoff
return 0;
}
if (g.takeoff_tdrag_elevator == 0) {
// no takeoff elevator set
goto return_zero;
}
if (auto_state.highest_airspeed >= g.takeoff_tdrag_speed1) {
// we've passed speed1. We now raise the tail and aim for
// level pitch. Return 0 meaning no fixed elevator setting
goto return_zero;
}
if (ahrs.pitch_sensor > auto_state.initial_pitch_cd + 1000) {
// the pitch has gone up by more then 10 degrees over the
// initial pitch. This may mean the nose is coming up for an
// early liftoff, perhaps due to a bad setting of
// g.takeoff_tdrag_speed1. Go to level flight to prevent a
// stall
goto return_zero;
}
// we are holding the tail down
return g.takeoff_tdrag_elevator;
return_zero:
if (auto_state.fbwa_tdrag_takeoff_mode) {
gcs_send_text(MAV_SEVERITY_NOTICE, "FBWA tdrag off");
auto_state.fbwa_tdrag_takeoff_mode = false;
}
return 0;
}
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/*
called when an auto-takeoff is complete
*/
void Plane::complete_auto_takeoff(void)
{
#if GEOFENCE_ENABLED == ENABLED
if (g.fence_autoenable > 0) {
if (! geofence_set_enabled(true, AUTO_TOGGLED)) {
gcs_send_text(MAV_SEVERITY_NOTICE, "Enable fence failed (cannot autoenable");
} else {
gcs_send_text(MAV_SEVERITY_INFO, "Fence enabled (autoenabled)");
}
}
#endif
}