Files
ardupilot/ArduPlane/mode_qrtl.cpp
T
Henry Wurzburg 3dc0c3621b Plane: QRTL: don't conflate altitude query failure with a zero delta
calc_alt_delta_m() returned 0 on failure indistinguishably from a
genuine zero delta. This poisoned the approach_start latch if the
query failed at latch time (silently disabling the descent ramp for
the rest of the approach), and folded a single failed query during
the per-cycle clamp into a target of rtl_alt_delta instead of simply
skipping the clamp for that cycle.

calc_alt_delta_m() now reports success/failure via a bool return and
an out-parameter. The latch only commits on success (valid stays
false to retry otherwise), and the clamp is skipped outright on a
failed cycle. Also stop the terrain-relative branch from falling
through to the absolute-altitude fallback when the terrain query
itself fails, which would otherwise mix an AMSL delta into a
terrain-relative ramp.
2026-08-25 09:39:19 +10:00

332 lines
15 KiB
C++

#include "mode.h"
#include "Plane.h"
#if HAL_QUADPLANE_ENABLED
bool ModeQRTL::_enter()
{
// treat QRTL as QLAND if we are in guided wait takeoff state, to cope
// with failsafes during GUIDED->AUTO takeoff sequence
if (plane.quadplane.guided_wait_takeoff_on_mode_enter) {
plane.set_mode(plane.mode_qland, ModeReason::QLAND_INSTEAD_OF_RTL);
return true;
}
submode = SubMode::RTL;
approach_start.valid = false;
plane.prev_WP_loc = plane.current_loc;
int32_t RTL_alt_abs_cm = plane.home.alt + quadplane.qrtl_alt_m*100UL;
if (quadplane.motors->get_desired_spool_state() == AP_Motors::DesiredSpoolState::THROTTLE_UNLIMITED) {
// VTOL motors are active, either in VTOL flight or assisted flight
Location destination = plane.calc_best_rally_or_home_location(plane.current_loc, RTL_alt_abs_cm);
const float dist = plane.current_loc.get_distance(destination);
const float radius = get_VTOL_return_radius();
// Climb at least to a cone around home of height of QRTL alt and radius of radius
// Always climb up to at least Q_RTL_ALT_MIN, constrain Q_RTL_ALT_MIN between Q_LAND_FINAL_ALT and Q_RTL_ALT
const float min_climb = constrain_float(quadplane.qrtl_alt_min_m, quadplane.land_final_alt_m, quadplane.qrtl_alt_m);
const float target_alt = MAX(quadplane.qrtl_alt_m * (dist / MAX(radius, dist)), min_climb);
#if AP_TERRAIN_AVAILABLE
const bool use_terrain = plane.terrain_enabled_in_mode(mode_number());
#else
const bool use_terrain = false;
#endif
const float dist_to_climb = target_alt - plane.relative_ground_altitude(RangeFinderUse::CLIMB, use_terrain);
if (is_positive(dist_to_climb)) {
// climb before returning, only next waypoint altitude is used
submode = SubMode::climb;
plane.next_WP_loc = plane.current_loc;
#if AP_TERRAIN_AVAILABLE
int32_t curent_alt_terrain_cm;
if (use_terrain && plane.current_loc.get_alt_cm(Location::AltFrame::ABOVE_TERRAIN, curent_alt_terrain_cm)) {
plane.next_WP_loc.set_alt_cm(curent_alt_terrain_cm + dist_to_climb * 100UL, Location::AltFrame::ABOVE_TERRAIN);
return true;
}
#endif
plane.next_WP_loc.set_alt_cm(plane.current_loc.alt + dist_to_climb * 100UL, plane.current_loc.get_alt_frame());
return true;
} else if (dist < radius) {
// Above home "cone", return at current altitude if lower than QRTL alt
int32_t current_alt_abs_cm;
if (plane.current_loc.get_alt_cm(Location::AltFrame::ABSOLUTE, current_alt_abs_cm)) {
RTL_alt_abs_cm = MIN(RTL_alt_abs_cm, current_alt_abs_cm);
}
// we're close to destination and already running VTOL motors, don't transition and don't climb
gcs().send_text(MAV_SEVERITY_INFO,"VTOL position1 d=%.1f r=%.1f", dist, radius);
poscontrol.set_state(QuadPlane::QPOS_POSITION1);
}
}
// use do_RTL() to setup next_WP_loc
plane.do_RTL(RTL_alt_abs_cm);
quadplane.poscontrol_init_approach();
int32_t from_alt;
int32_t to_alt;
if (plane.current_loc.get_alt_cm(Location::AltFrame::ABSOLUTE,from_alt) && plane.next_WP_loc.get_alt_cm(Location::AltFrame::ABSOLUTE,to_alt)) {
poscontrol.slow_descent = from_alt > to_alt;
return true;
}
// default back to old method
poscontrol.slow_descent = (plane.current_loc.alt > plane.next_WP_loc.alt);
return true;
}
void ModeQRTL::update()
{
plane.mode_qstabilize.update();
}
/*
handle QRTL mode
*/
void ModeQRTL::run()
{
const uint32_t now = AP_HAL::millis();
if (quadplane.tailsitter.in_vtol_transition(now)) {
// Tailsitters in FW pull up phase of VTOL transition run FW controllers
Mode::run();
return;
}
switch (submode) {
case SubMode::climb: {
// request zero velocity
Vector2f vel, accel;
pos_control->input_vel_accel_NE_m(vel, accel);
quadplane.run_xy_controller();
// nav roll and pitch are controller by position controller
plane.nav_roll_cd = pos_control->get_roll_cd();
plane.nav_pitch_cd = pos_control->get_pitch_cd();
plane.quadplane.assign_tilt_to_fwd_thr();
if (quadplane.transition->set_VTOL_roll_pitch_limit(plane.nav_roll_cd, plane.nav_pitch_cd)) {
pos_control->NE_set_externally_limited();
}
// weathervane with no pilot input
quadplane.disable_yaw_rate_time_constant();
attitude_control->input_euler_angle_roll_pitch_euler_rate_yaw_cd(plane.nav_roll_cd,
plane.nav_pitch_cd,
quadplane.get_weathervane_yaw_rate_cds());
// climb at full WP nav speed
quadplane.set_climb_rate_ms(quadplane.wp_nav->get_default_speed_up_ms());
quadplane.run_z_controller();
// Climb done when stopping point reaches target altitude
Vector3p stopping_point_ned_m;
pos_control->get_stopping_point_D_m(stopping_point_ned_m.z);
Location stopping_loc = Location::from_ekf_offset_NED_m(stopping_point_ned_m, Location::AltFrame::ABOVE_ORIGIN);
ftype alt_diff;
if (!stopping_loc.get_height_above(plane.next_WP_loc, alt_diff) || is_positive(alt_diff)) {
// climb finished or cant get alt diff, head home
submode = SubMode::RTL;
plane.prev_WP_loc = plane.current_loc;
int32_t RTL_alt_abs_cm = plane.home.alt + quadplane.qrtl_alt_m*100UL;
Location destination = plane.calc_best_rally_or_home_location(plane.current_loc, RTL_alt_abs_cm);
const float dist = plane.current_loc.get_distance(destination);
const float radius = get_VTOL_return_radius();
if (dist < radius) {
// if close to home return at current target altitude
int32_t target_alt_abs_cm;
if (plane.next_WP_loc.get_alt_cm(Location::AltFrame::ABSOLUTE, target_alt_abs_cm)) {
RTL_alt_abs_cm = MIN(RTL_alt_abs_cm, target_alt_abs_cm);
}
gcs().send_text(MAV_SEVERITY_INFO,"VTOL position1 d=%.1f r=%.1f", dist, radius);
poscontrol.set_state(QuadPlane::QPOS_POSITION1);
}
plane.do_RTL(RTL_alt_abs_cm);
quadplane.poscontrol_init_approach();
if (plane.current_loc.get_height_above(plane.next_WP_loc, alt_diff)) {
poscontrol.slow_descent = is_positive(alt_diff);
} else {
// default back to old method
poscontrol.slow_descent = (plane.current_loc.alt > plane.next_WP_loc.alt);
}
}
break;
}
case SubMode::RTL: {
quadplane.vtol_position_controller();
if (poscontrol.get_state() > QuadPlane::QPOS_POSITION2) {
// change target altitude to home alt
plane.next_WP_loc.copy_alt_from(plane.home);
}
if (poscontrol.get_state() >= QuadPlane::QPOS_POSITION2) {
// start landing logic
quadplane.verify_vtol_land();
}
// when in approach allow stick mixing
if (quadplane.poscontrol.get_state() == QuadPlane::QPOS_AIRBRAKE ||
quadplane.poscontrol.get_state() == QuadPlane::QPOS_APPROACH) {
plane.stabilize_stick_mixing_fbw();
}
break;
}
}
// Stabilize with fixed wing surfaces
plane.stabilize_roll();
plane.stabilize_pitch();
plane.stabilize_yaw();
}
/*
return current height above the QRTL destination altitude, in the same
frame (terrain-relative if QRTL is terrain following, else absolute) the
approach altitude ramp in update_target_altitude() is applied in.
Returns false, leaving alt_delta_m unchanged, if no usable altitude data
is available -- callers must not treat that the same as a zero delta
*/
bool ModeQRTL::calc_alt_delta_m(float &alt_delta_m) const
{
#if AP_TERRAIN_AVAILABLE
if (plane.next_WP_loc.terrain_alt) {
// QRTL is terrain following: compute the delta in the same
// terrain-relative frame the ramp is applied in via
// change_target_altitude(), so the two stay consistent over
// sloping ground. next_WP_loc.alt is already the destination's
// own terrain-relative target height, in cm. Don't fall back to
// the absolute-altitude path below on failure -- that would mix
// an AMSL delta into a terrain-relative ramp
float current_terrain_height_m;
if (!plane.terrain.height_above_terrain(current_terrain_height_m, true)) {
return false;
}
alt_delta_m = current_terrain_height_m - (plane.next_WP_loc.alt * 0.01);
return true;
}
#endif
int32_t current_alt_cm;
int32_t dest_alt_cm;
if (plane.current_loc.get_alt_cm(Location::AltFrame::ABSOLUTE, current_alt_cm) &&
plane.next_WP_loc.get_alt_cm(Location::AltFrame::ABSOLUTE, dest_alt_cm)) {
alt_delta_m = (current_alt_cm - dest_alt_cm) * 0.01;
return true;
}
// no usable altitudes
return false;
}
/*
update target altitude for QRTL profile
*/
void ModeQRTL::update_target_altitude()
{
/*
update height target in approach. This continues through the airbrake,
POSITION1 and POSITION2 stages -- the same window in which TECS keeps
running (see QuadPlane::should_disable_TECS()) -- so that the altitude
TECS is using is never stepped while an abrupt transition out of
APPROACH/AIRBRAKE (e.g. thrust loss, low airspeed, bad attitude) can
happen well before the ramp has reached RTL_ALTITUDE
*/
const QuadPlane::position_control_state qpos_state = plane.quadplane.poscontrol.get_state();
if ((submode != SubMode::RTL) ||
(qpos_state < QuadPlane::QPOS_APPROACH) || (qpos_state > QuadPlane::QPOS_POSITION2)) {
Mode::update_target_altitude();
return;
}
/*
initially approach at RTL_ALT_CM, then drop down to QRTL_ALT based on maximum sink rate from TECS,
giving time to lose speed before we transition
*/
const float radius = MAX(fabsf(float(plane.aparm.loiter_radius)), fabsf(float(plane.g.rtl_radius)));
const float rtl_alt_delta = MAX(0, plane.g.RTL_altitude - plane.quadplane.qrtl_alt_m);
const float sink_time = rtl_alt_delta / MAX(0.6*plane.TECS_controller.get_max_sinkrate(), 1);
const float sink_dist = plane.aparm.airspeed_cruise * sink_time;
const float dist = plane.auto_state.wp_distance;
const float rad_min = 2*radius;
const float rad_max = 20*radius;
const float dist_rtl_alt_reached = MAX(rad_min, MIN(rad_max, rad_min+sink_dist));
if (!approach_start.valid) {
// latch where the approach began, so the ramp below is driven by our
// own altitude at the start of the approach rather than the fixed wing
// waypoint offset, which is cleared as the destination is neared.
// If the altitude query fails, leave valid false so we retry next
// cycle rather than latching a bogus zero delta that would silently
// disable the ramp for the rest of the approach
if (calc_alt_delta_m(approach_start.alt_delta_m)) {
approach_start.dist_m = dist;
approach_start.valid = true;
}
}
// Set the target altitude to the QRTL altitude
plane.set_target_altitude_location(plane.next_WP_loc);
float alt;
if (dist > dist_rtl_alt_reached) {
/*
still well short of home: instead of immediately targeting RTL_ALTITUDE,
gradually descend from the altitude we were at when this approach leg
started down to RTL_ALTITUDE, reaching it at dist_rtl_alt_reached.
As for fixed wing waypoints, ALT_SLOPE_MIN gates this: setting it to
zero disables the gradual descent, and altitude changes smaller than
it are made immediately
*/
const float alt_excess = approach_start.valid ? (approach_start.alt_delta_m - rtl_alt_delta) : 0;
if (approach_start.valid && (plane.g.alt_slope_min > 0) && (alt_excess >= plane.g.alt_slope_min) &&
(approach_start.dist_m > dist_rtl_alt_reached)) {
alt = linear_interpolate(rtl_alt_delta, approach_start.alt_delta_m,
dist,
dist_rtl_alt_reached, approach_start.dist_m);
// The ramp above is driven purely by the latched start point and
// distance, so it doesn't know if we've since fallen below its
// line, e.g. QRTL was entered while already sinking briskly. In
// that case don't command a climb back up to the ramp -- follow
// the aircraft down instead, floored at rtl_alt_delta so this
// branch hands off to the dist_rtl_alt_reached boundary below at
// the same altitude that boundary itself targets (still permits
// climbing back to rtl_alt_delta if we're currently below it,
// same as the pre-ramp behaviour of targeting RTL_ALTITUDE outright).
// If this cycle's altitude query fails, skip the clamp rather than
// folding the failure into a target of rtl_alt_delta
float current_alt_delta_m;
if (calc_alt_delta_m(current_alt_delta_m)) {
alt = MIN(alt, MAX(rtl_alt_delta, current_alt_delta_m));
}
} else {
// gradual descent disabled, nothing worth ramping down from, or
// the altitude query has never yet succeeded this approach
alt = rtl_alt_delta;
}
} else {
// Close to home, descend from RTL alt to QRTL alt
alt = linear_interpolate(0.0, rtl_alt_delta,
dist,
rad_min, dist_rtl_alt_reached);
}
// Adjust target altitude based on distance to home
plane.change_target_altitude(alt * 100);
}
// only nudge during approach
bool ModeQRTL::allows_throttle_nudging() const
{
return (submode == SubMode::RTL) && (plane.quadplane.poscontrol.get_state() == QuadPlane::QPOS_APPROACH);
}
// Return the radius from destination at which pure VTOL flight should be used, no transition to FW
float ModeQRTL::get_VTOL_return_radius() const
{
return MAX(fabsf(float(plane.aparm.loiter_radius)), fabsf(float(plane.g.rtl_radius))) * 1.5;
}
#endif