mirror of https://github.com/ArduPilot/ardupilot
55 lines
2.1 KiB
C++
55 lines
2.1 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 = get_distance(rover.current_loc, _destination);
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// if within waypoint radius slew desired speed towards zero and use existing desired heading
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if (_distance_to_destination <= g.waypoint_radius) {
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_desired_speed = attitude_control.get_desired_speed_accel_limited(0.0f, 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 - g.waypoint_radius) * 0.5f, g.speed_cruise);
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// calculate bearing to destination
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_desired_yaw_cd = get_bearing_cd(rover.current_loc, _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) {
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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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// note: copied from calc_reduced_speed_for_turn_or_distance
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float yaw_error_ratio = 1.0f - constrain_float(fabsf(_yaw_error_cd / 9000.0f), 0.0f, 1.0f) * ((100.0f - g.speed_turn_gain) * 0.01f);
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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, _desired_speed < 0);
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calc_throttle(_desired_speed, false, true);
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}
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