ardupilot/ArduPlane/is_flying.cpp

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
#include "Plane.h"
/*
is_flying and crash detection logic
*/
/*
Do we think we are flying?
Probabilistic method where a bool is low-passed and considered a probability.
*/
void Plane::update_is_flying_5Hz(void)
{
float aspeed;
bool is_flying_bool;
uint32_t now_ms = hal.scheduler->millis();
uint32_t ground_speed_thresh_cm = (g.min_gndspeed_cm > 0) ? ((uint32_t)(g.min_gndspeed_cm*0.9f)) : 500;
bool gps_confirmed_movement = (gps.status() >= AP_GPS::GPS_OK_FIX_3D) &&
(gps.ground_speed_cm() >= ground_speed_thresh_cm);
// airspeed at least 75% of stall speed?
bool airspeed_movement = ahrs.airspeed_estimate(&aspeed) && (aspeed >= (aparm.airspeed_min*0.75f));
if(arming.is_armed()) {
// when armed assuming flying and we need overwhelming evidence that we ARE NOT flying
// short drop-outs of GPS are common during flight due to banking which points the antenna in different directions
bool gps_lost_recently = (gps.last_fix_time_ms() > 0) && // we have locked to GPS before
(gps.status() < AP_GPS::GPS_OK_FIX_2D) && // and it's lost now
(now_ms - gps.last_fix_time_ms() < 5000); // but it wasn't that long ago (<5s)
if ((auto_state.last_flying_ms > 0) && gps_lost_recently) {
// we've flown before, remove GPS constraints temporarily and only use airspeed
is_flying_bool = airspeed_movement; // moving through the air
} else {
// we've never flown yet, require good GPS movement
is_flying_bool = airspeed_movement || // moving through the air
gps_confirmed_movement; // locked and we're moving
}
if (control_mode == AUTO) {
/*
make is_flying() more accurate during various auto modes
*/
switch (flight_stage)
{
case AP_SpdHgtControl::FLIGHT_TAKEOFF:
// while on the ground, an uncalibrated airspeed sensor can drift to 7m/s so
// ensure we aren't showing a false positive. If the throttle is suppressed
// we are definitely not flying, or at least for not much longer!
if (throttle_suppressed) {
is_flying_bool = false;
crash_state.is_crashed = false;
}
break;
case AP_SpdHgtControl::FLIGHT_LAND_ABORT:
case AP_SpdHgtControl::FLIGHT_NORMAL:
// TODO: detect ground impacts
break;
case AP_SpdHgtControl::FLIGHT_LAND_APPROACH:
// TODO: detect ground impacts
if (fabsf(auto_state.sink_rate) > 0.2f) {
is_flying_bool = true;
}
break;
case AP_SpdHgtControl::FLIGHT_LAND_FINAL:
break;
} // switch
}
} else {
// when disarmed assume not flying and need overwhelming evidence that we ARE flying
is_flying_bool = airspeed_movement && gps_confirmed_movement;
if ((control_mode == AUTO) &&
((flight_stage == AP_SpdHgtControl::FLIGHT_TAKEOFF) ||
(flight_stage == AP_SpdHgtControl::FLIGHT_LAND_FINAL)) ) {
is_flying_bool = false;
}
}
// low-pass the result.
// coef=0.15f @ 5Hz takes 3.0s to go from 100% down to 10% (or 0% up to 90%)
isFlyingProbability = (0.85f * isFlyingProbability) + (0.15f * (float)is_flying_bool);
/*
update last_flying_ms so we always know how long we have not
been flying for. This helps for crash detection and auto-disarm
*/
bool new_is_flying = is_flying();
// we are flying, note the time
if (new_is_flying) {
auto_state.last_flying_ms = now_ms;
if (!previous_is_flying) {
// just started flying in any mode
started_flying_ms = now_ms;
}
if ((control_mode == AUTO) &&
((auto_state.started_flying_in_auto_ms == 0) || !previous_is_flying) ) {
// We just started flying, note that time also
auto_state.started_flying_in_auto_ms = now_ms;
}
}
previous_is_flying = new_is_flying;
if (should_log(MASK_LOG_MODE)) {
Log_Write_Status();
}
}
/*
return true if we think we are flying. This is a probabilistic
estimate, and needs to be used very carefully. Each use case needs
to be thought about individually.
*/
bool Plane::is_flying(void)
{
if (hal.util->get_soft_armed()) {
// when armed, assume we're flying unless we probably aren't
return (isFlyingProbability >= 0.1f);
}
// when disarmed, assume we're not flying unless we probably are
return (isFlyingProbability >= 0.9f);
}
/*
* Determine if we have crashed
*/
void Plane::crash_detection_update(void)
{
if (control_mode != AUTO)
{
// crash detection is only available in AUTO mode
crash_state.debounce_timer_ms = 0;
return;
}
uint32_t now_ms = hal.scheduler->millis();
bool auto_launch_detected;
bool crashed_near_land_waypoint = false;
bool crashed = false;
bool been_auto_flying = (auto_state.started_flying_in_auto_ms > 0) &&
(now_ms - auto_state.started_flying_in_auto_ms >= 2500);
if (!is_flying())
{
switch (flight_stage)
{
case AP_SpdHgtControl::FLIGHT_TAKEOFF:
auto_launch_detected = !throttle_suppressed && (g.takeoff_throttle_min_accel > 0);
if (been_auto_flying || // failed hand launch
auto_launch_detected) { // threshold of been_auto_flying may not be met on auto-launches
// has launched but is no longer flying. That's a crash on takeoff.
crashed = true;
}
break;
case AP_SpdHgtControl::FLIGHT_LAND_ABORT:
case AP_SpdHgtControl::FLIGHT_NORMAL:
if (been_auto_flying) {
crashed = true;
}
// TODO: handle auto missions without NAV_TAKEOFF mission cmd
break;
case AP_SpdHgtControl::FLIGHT_LAND_APPROACH:
if (been_auto_flying) {
crashed = true;
}
// when altitude gets low, we automatically progress to FLIGHT_LAND_FINAL
// so ground crashes most likely can not be triggered from here. However,
// a crash into a tree, for example, would be.
break;
case AP_SpdHgtControl::FLIGHT_LAND_FINAL:
// We should be nice and level-ish in this flight stage. If not, we most
// likely had a crazy landing. Throttle is inhibited already at the flare
// but go ahead and notify GCS and perform any additional post-crash actions.
// Declare a crash if we are oriented more that 60deg in pitch or roll
if (been_auto_flying &&
!crash_state.checkHardLanding && // only check once
(fabsf(ahrs.roll_sensor) > 6000 || fabsf(ahrs.pitch_sensor) > 6000)) {
crashed = true;
// did we "crash" within 75m of the landing location? Probably just a hard landing
crashed_near_land_waypoint =
get_distance(current_loc, mission.get_current_nav_cmd().content.location) < 75;
// trigger hard landing event right away, or never again. This inhibits a false hard landing
// event when, for example, a minute after a good landing you pick the plane up and
// this logic is still running and detects the plane is on its side as you carry it.
crash_state.debounce_timer_ms = now_ms + 2500;
}
crash_state.checkHardLanding = true;
break;
} // switch
} else {
crash_state.checkHardLanding = false;
}
if (!crashed) {
// reset timer
crash_state.debounce_timer_ms = 0;
} else if (crash_state.debounce_timer_ms == 0) {
// start timer
crash_state.debounce_timer_ms = now_ms;
} else if ((now_ms - crash_state.debounce_timer_ms >= 2500) && !crash_state.is_crashed) {
crash_state.is_crashed = true;
if (g.crash_detection_enable == CRASH_DETECT_ACTION_BITMASK_DISABLED) {
if (crashed_near_land_waypoint) {
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gcs_send_text_P(MAV_SEVERITY_CRITICAL, PSTR("Hard Landing Detected - no action taken"));
} else {
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gcs_send_text_P(MAV_SEVERITY_CRITICAL, PSTR("Crash Detected - no action taken"));
}
}
else {
if (g.crash_detection_enable & CRASH_DETECT_ACTION_BITMASK_DISARM) {
disarm_motors();
}
auto_state.land_complete = true;
if (crashed_near_land_waypoint) {
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gcs_send_text_P(MAV_SEVERITY_CRITICAL, PSTR("Hard Landing Detected"));
} else {
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gcs_send_text_P(MAV_SEVERITY_CRITICAL, PSTR("Crash Detected"));
}
}
}
}