mirror of https://github.com/ArduPilot/ardupilot
57 lines
2.2 KiB
C++
57 lines
2.2 KiB
C++
#include "mode.h"
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#include "Rover.h"
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bool ModeLoiter::_enter()
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{
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// set _destination to reasonable stopping point
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calc_stopping_location(_destination);
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// initialise desired speed to current speed
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if (!attitude_control.get_forward_speed(_desired_speed)) {
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_desired_speed = 0.0f;
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}
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// initialise heading to current heading
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_desired_yaw_cd = ahrs.yaw_sensor;
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_yaw_error_cd = 0.0f;
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return true;
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}
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void ModeLoiter::update()
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{
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// get distance (in meters) to destination
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_distance_to_destination = rover.current_loc.get_distance(_destination);
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// if within loiter radius slew desired speed towards zero and use existing desired heading
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if (_distance_to_destination <= g2.loit_radius) {
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// sailboats do not stop
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const float desired_speed_within_radius = g2.motors.has_sail() ? 0.1f : 0.0f;
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_desired_speed = attitude_control.get_desired_speed_accel_limited(desired_speed_within_radius, rover.G_Dt);
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_yaw_error_cd = 0.0f;
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} else {
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// P controller with hard-coded gain to convert distance to desired speed
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// To-Do: make gain configurable or calculate from attitude controller's maximum accelearation
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_desired_speed = MIN((_distance_to_destination - g2.loit_radius) * 0.5f, g.speed_cruise);
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// calculate bearing to destination
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_desired_yaw_cd = rover.current_loc.get_bearing_to(_destination);
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_yaw_error_cd = wrap_180_cd(_desired_yaw_cd - ahrs.yaw_sensor);
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// if destination is behind vehicle, reverse towards it
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if (fabsf(_yaw_error_cd) > 9000 && g2.loit_type == 0) {
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_desired_yaw_cd = wrap_180_cd(_desired_yaw_cd + 18000);
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_yaw_error_cd = wrap_180_cd(_desired_yaw_cd - ahrs.yaw_sensor);
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_desired_speed = -_desired_speed;
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}
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// reduce desired speed if yaw_error is large
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// 45deg of error reduces speed to 75%, 90deg of error reduces speed to 50%
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float yaw_error_ratio = 1.0f - constrain_float(fabsf(_yaw_error_cd / 9000.0f), 0.0f, 1.0f) * 0.5f;
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_desired_speed *= yaw_error_ratio;
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}
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// run steering and throttle controllers
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calc_steering_to_heading(_desired_yaw_cd);
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calc_throttle(_desired_speed, false, true);
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}
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