ardupilot/ArduPlane/mode_loiter.cpp

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#include "mode.h"
#include "Plane.h"
bool ModeLoiter::_enter()
{
plane.do_loiter_at_location();
plane.loiter_angle_reset();
return true;
}
void ModeLoiter::update()
{
plane.calc_nav_roll();
plane.calc_nav_pitch();
plane.calc_throttle();
}
bool ModeLoiter::isHeadingLinedUp(const Location loiterCenterLoc, const Location targetLoc)
{
// Return true if current heading is aligned to vector to targetLoc.
// Tolerance is initially 10 degrees and grows at 10 degrees for each loiter circle completed.
const uint16_t loiterRadius = abs(plane.aparm.loiter_radius);
if (loiterCenterLoc.get_distance(targetLoc) < loiterRadius + loiterRadius*0.05) {
/* Whenever next waypoint is within the loiter radius plus 5%,
maintaining loiter would prevent us from ever pointing toward the next waypoint.
Hence break out of loiter immediately
*/
return true;
}
// Bearing in centi-degrees
const int32_t bearing_cd = plane.current_loc.get_bearing_to(targetLoc);
return isHeadingLinedUp_cd(bearing_cd);
}
bool ModeLoiter::isHeadingLinedUp_cd(const int32_t bearing_cd)
{
// Return true if current heading is aligned to bearing_cd.
// Tolerance is initially 10 degrees and grows at 10 degrees for each loiter circle completed.
// get current heading.
const int32_t heading_cd = (wrap_360(degrees(plane.ahrs.groundspeed_vector().angle())))*100;
const int32_t heading_err_cd = wrap_180_cd(bearing_cd - heading_cd);
/*
Check to see if the the plane is heading toward the land
waypoint. We use 20 degrees (+/-10 deg) of margin so that
we can handle 200 degrees/second of yaw.
After every full circle, extend acceptance criteria to ensure
aircraft will not loop forever in case high winds are forcing
it beyond 200 deg/sec when passing the desired exit course
*/
// Use integer division to get discrete steps
const int32_t expanded_acceptance = 1000 * (labs(plane.loiter.sum_cd) / 36000);
if (labs(heading_err_cd) <= 1000 + expanded_acceptance) {
// Want to head in a straight line from _here_ to the next waypoint instead of center of loiter wp
// 0 to xtrack from center of waypoint, 1 to xtrack from tangent exit location
if (plane.next_WP_loc.loiter_xtrack) {
plane.next_WP_loc = plane.current_loc;
}
return true;
}
return false;
}
void ModeLoiter::navigate()
{
// Zero indicates to use WP_LOITER_RAD
plane.update_loiter(0);
}